runtime: clarify runtime.GC blocking behavior
runtime: clarify runtime.GC blocking behavior

The runtime.GC documentation was rewritten in df2809f to make it clear
that it blocks until GC is complete, but the re-rewrite in ed9a4c9 and
e28a679 lost this property when clarifying that it may also block the
entire program and not just the caller.

Try to arrive at wording that conveys both of these properties.

Change-Id: I1e255322aa28a21a548556ecf2a44d8d8ac524ef
Reviewed-on: https://go-review.googlesource.com/12392
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

zcwfeng/go,snowsnail/go,skotti/go,ObjectiveJoe/go,Cofyc/go,cainiaocome/go,danycoro/go,golang/go,arschles/golang-go,Endika/go,XuYunnan/go,theif519/go,miolini/go,cloudflare/go,xujianhai/go,uileyar/go,xinhuang327/go,fjballest/golang,arschles/go-1,pgmreddy/go,mdp/go,josharian/go,sosop/go,jonahglover/go,sndnvaps/go,chinanjjohn2012/go,jonahglover/go,jonasi/go,GeorgiCodes/go,albertjin/golang-go,jmptrader/go,mwhudson/go,Badredapple/go,dgnorton/go,cloudflare/go,RBEGamer/go,goodlang/good,cloudrain21/go,dterei/go,miolini/go,baiyunping333/go,mgyenik/go,malvira/go,arschles/golang-go,danielsoro/go,mwhudson/go,Cofyc/go,Pulgafree/go,agaurav/go,Samurais/go,rachtsingh/gogojuice,youprofit/go,mwhudson/go,sosop/go,Jordanzuo/go,Samurais/go,kim-racktop/go,JioCloud/go,jameskumar/go,xinhuang327/go,mgyenik/go,miolini/go,joshsammut/go,skatsuta/go,theass/go,codestation/go,greyhwndz/go,theass/go,willjunspecial/go,goodlang/good,qskycolor/go,alash3al/go,xiuzhifu/go,jacobxk/go,leeric92/go,zcwfeng/go,donnel6809/go,mbrukman/go,malvira/go,rentongzhang/go,malvira/go,mgyenik/go,arschles/golang-go,CodyGuo/go,constantine001/go,sinuos/go,vsekhar/elastic-go,arschles/golang-go,donnel6809/go,danielsoro/go,cloudrain21/go,skatsuta/go,rachtsingh/gogojuice,AALEKH/go,sinuos/go,ErikDubbelboer/go,skotti/go,dafyddcrosby/go,Samurais/go,mwhudson/go,joshsammut/go,ichu501/go,xinhuang327/go,yangzhongj/go,vishsingh/go,b54898533/go,agaurav/go,GeorgiCodes/go,cookerzhu/go,dpatel06/go,b54898533/go,CodyGuo/go,4ad/go,Young55555/go,undergrowthlinear/go,andrewchambers/go,myPublicGit/go,mbrukman/go,uileyar/go,4ad/go,xinhuang327/go,jonathanmarvens/go,mdp/go,mikekap/go,famorted/go,zouchao2010/go,devpadawan/go,Jordanzuo/go,nawawi/go,dgnorton/go,Cofyc/go,stormltf/go,ganboing/go-esx,Badredapple/go,jonasi/go,Badredapple/go,parkdy/go,baiyunping333/go,mbrukman/go,jasonxiong/go,stormltf/go,cnbin/go,odeke-em/go,alex-zhang/go,jameskumar/go,jdeng/go,xinhuang327/go,leeric92/go,myPublicGit/go,jacobhaven/go,kim-racktop/go,springning/go,theif519/go,jdhenke/go,cookerzhu/go,jonahglover/go,wangfakang/go-1,kakuhiroshi/go,samanalysis/go,jacobsa/go,mgyenik/go,kakuhiroshi/go,polyverse-security/go,willjunspecial/go,mgyenik/go,andrewchambers/go,Charlesdong/go-1,ganboing/go-esx,rachtsingh/gogojuice,yasarkunduz/go,ichu501/go,fjballest/golang,stormltf/go,dpatel06/go,dterei/go,malvira/go,danielsoro/go,jdeng/go,akutz/go,sndnvaps/go,ImJasonH/go,joshsammut/go,codestation/go,CarterTsai/go,cnbin/go,cainiaocome/go,binarycrusader/go,yuhengye/go,lihuanghai/go,christopher-henderson/Go,dterei/go,ifagnosticism/go,youprofit/go,goodlang/good,shazow/go,danielsoro/go,kevinc0825/go,lihuanghai/go,CarterTsai/go,Samurais/go,binarycrusader/go,WIZARD-CXY/go,slavau/go,greyhwndz/go,nawawi/go,kakuhiroshi/go,jasonxiong/go,donnel6809/go,Pulgafree/go,sndnvaps/go,vishsingh/go,ErikDubbelboer/go,Jordanzuo/go,JioCloud/go,arschles/go-1,Young55555/go,xinhuang327/go,agaurav/go,zcwfeng/go,shines77/go,codestation/go,yangzhongj/go,jdeng/go,wangfakang/go-1,skotti/go,dafyddcrosby/go,sosop/go,NunoEdgarGub1/go,theif519/go,baiyunping333/go,shines77/go,leeric92/go,slavau/go,goodlang/good,CiscoCloud/go,springning/go,akutz/go,NichoZhang/go,ericsnowcurrently/go,alex-zhang/go,Young55555/go,leeric92/go,CAFxX/go,dgnorton/go,greyhwndz/go,akutz/go,ObjectiveJoe/go,dkolbly/go,stormltf/go,jameskumar/go,linux-on-ibm-z/go,dterei/go,suncycheng/go,odeke-em/go,yuhengye/go,NunoEdgarGub1/go,deft-code/go,JioCloud/go,suncycheng/go,zcwfeng/go,parkdy/go,CiscoCloud/go,golang/go,baiyunping333/go,cloudflare/go,odeke-em/go,ImJasonH/go,ImJasonH/go,vsekhar/elastic-go,Charlesdong/go-1,wangfakang/go-1,g522342435/go,RBEGamer/go,undergrowthlinear/go,zhangg/go,snowsnail/go,NichoZhang/go,yangzhongj/go,ganboing/go-esx,deft-code/go,skotti/go,jacobsa/go,myPublicGit/go,CodyGuo/go,dkolbly/go,wangfakang/go-1,yuhengye/go,ichu501/go,ifagnosticism/go,shazow/go,gohin/go,yangzhongj/go,fjballest/golang,NichoZhang/go,akutz/go,mikekap/go,Pulgafree/go,ifagnosticism/go,xiuzhifu/go,ganboing/go-esx,donnel6809/go,parkdy/go,wangfakang/go-1,jmptrader/go,snowsnail/go,nawawi/go,zhangg/go,ObjectiveJoe/go,kakuhiroshi/go,shines77/go,constantine001/go,mbrukman/go,springning/go,danycoro/go,fjballest/golang,Cofyc/go,danycoro/go,chinanjjohn2012/go,WIZARD-CXY/go,vsekhar/elastic-go,cloudflare/go,theif519/go,momchil-velikov/go,jmptrader/go,yasarkunduz/go,nawawi/go,arschles/go-1,arschles/golang-go,honsiorovskyi/go,4ad/go,CarterTsai/go,youprofit/go,cnbin/go,kakuhiroshi/go,theif519/go,slavau/go,dterei/go,sndnvaps/go,CodyGuo/go,mwhudson/go,monetate/go,vanloswang/go,jdeng/go,skatsuta/go,danycoro/go,zcwfeng/go,Pulgafree/go,xiuzhifu/go,derekmarcotte/go,monetate/go,lihuanghai/go,ganboing/go-esx,jdeng/go,honsiorovskyi/go,Charlesdong/go-1,rentongzhang/go,jonasi/go,XuYunnan/go,samanalysis/go,xujianhai/go,RBEGamer/go,andrewchambers/go,vsekhar/elastic-go,parkdy/go,jdhenke/go,vsdutka/go,josharian/go,skotti/go,jdhenke/go,beealone/go,mbrukman/go,springning/go,sndnvaps/go,cyberroadie/go,devpadawan/go,linux-on-ibm-z/go,rentongzhang/go,WIZARD-CXY/go,Cofyc/go,mwhudson/go,parkdy/go,gohin/go,joshsammut/go,shazow/go,rentongzhang/go,devpadawan/go,nakedgc/go,b54898533/go,RBEGamer/go,JioCloud/go,ericsnowcurrently/go,Endika/go,jameskumar/go,kim-racktop/go,xiuzhifu/go,polyverse-security/go,codestation/go,jonathanmarvens/go,alash3al/go,jasonxiong/go,arschles/golang-go,slavau/go,suncycheng/go,vishsingh/go,cnbin/go,zouchao2010/go,jameskumar/go,alash3al/go,dgnorton/go,jonathanmarvens/go,likesea/go,CiscoCloud/go,GeorgiCodes/go,shazow/go,Cofyc/go,pgmreddy/go,suncycheng/go,yangzhongj/go,cainiaocome/go,yasarkunduz/go,donnel6809/go,jacobsa/go,AALEKH/go,xiaobodu/go,CodyGuo/go,ObjectiveJoe/go,shines77/go,nakedgc/go,springning/go,sinuos/go,ObjectiveJoe/go,Endika/go,jacobhaven/go,g522342435/go,cloudflare/go,nakedgc/go,CarterTsai/go,cookerzhu/go,roth1002/go,xiaobodu/go,shines77/go,uileyar/go,youprofit/go,undergrowthlinear/go,theif519/go,nawawi/go,cloudflare/go,chinanjjohn2012/go,pgmreddy/go,yasarkunduz/go,baiyunping333/go,zouchao2010/go,devpadawan/go,nawawi/go,sinuos/go,ErikDubbelboer/go,ganboing/go-esx,greyhwndz/go,XuYunnan/go,cainiaocome/go,golang/go,yasarkunduz/go,Badredapple/go,jmptrader/go,roth1002/go,b54898533/go,yasarkunduz/go,pgmreddy/go,youprofit/go,willjunspecial/go,b54898533/go,jonasi/go,qskycolor/go,mdp/go,RBEGamer/go,Jordanzuo/go,derekmarcotte/go,cloudrain21/go,jdhenke/go,uileyar/go,youprofit/go,arschles/golang-go,donnel6809/go,chinanjjohn2012/go,Stan-Lin-/go,danycoro/go,momchil-velikov/go,zhangg/go,dpatel06/go,honsiorovskyi/go,theass/go,xiaobodu/go,Young55555/go,zhangg/go,jacobsa/go,vishsingh/go,slavau/go,famorted/go,mikekap/go,zcwfeng/go,samanalysis/go,Stan-Lin-/go,ErikDubbelboer/go,jonahglover/go,codestation/go,dgnorton/go,nawawi/go,skatsuta/go,ErikDubbelboer/go,golang/go,linux-on-ibm-z/go,AALEKH/go,fjballest/golang,qskycolor/go,uileyar/go,odeke-em/go,jacobhaven/go,ifagnosticism/go,jonathanmarvens/go,xiuzhifu/go,stormltf/go,famorted/go,Young55555/go,mgyenik/go,dkolbly/go,NunoEdgarGub1/go,danielsoro/go,cloudrain21/go,mdp/go,cyberroadie/go,jacobxk/go,gohin/go,vishsingh/go,jacobxk/go,famorted/go,ericsnowcurrently/go,AALEKH/go,mdp/go,dgnorton/go,theass/go,honsiorovskyi/go,b54898533/go,akutz/go,vanloswang/go,willjunspecial/go,agaurav/go,samanalysis/go,willjunspecial/go,kim-racktop/go,derekmarcotte/go,ericsnowcurrently/go,kevinc0825/go,polyverse-security/go,xujianhai/go,albertjin/golang-go,jefby/go,yasarkunduz/go,yuhengye/go,cloudflare/go,snowsnail/go,albertjin/golang-go,jefby/go,gdey/go,xujianhai/go,mgyenik/go,ErikDubbelboer/go,lihuanghai/go,vanloswang/go,cyberroadie/go,codestation/go,CAFxX/go,jacobxk/go,cainiaocome/go,jonathanmarvens/go,suncycheng/go,suncycheng/go,andrewchambers/go,cookerzhu/go,ObjectiveJoe/go,WIZARD-CXY/go,jasonxiong/go,AALEKH/go,sosop/go,pgmreddy/go,codestation/go,zhangg/go,honsiorovskyi/go,cloudrain21/go,zcwfeng/go,kevinc0825/go,mdp/go,jonahglover/go,momchil-velikov/go,Charlesdong/go-1,willjunspecial/go,cyberroadie/go,JioCloud/go,pgmreddy/go,polyverse-security/go,rentongzhang/go,xiaobodu/go,goodlang/good,monetate/go,jameskumar/go,baiyunping333/go,jonasi/go,uileyar/go,jdhenke/go,vsekhar/elastic-go,linux-on-ibm-z/go,honsiorovskyi/go,gdey/go,jdhenke/go,danielsoro/go,CodyGuo/go,jacobhaven/go,Pulgafree/go,RBEGamer/go,nakedgc/go,ganboing/go-esx,vsdutka/go,jacobsa/go,arschles/go-1,g522342435/go,chinanjjohn2012/go,cnbin/go,zhangg/go,deft-code/go,mikekap/go,leeric92/go,zouchao2010/go,alash3al/go,mikekap/go,jacobhaven/go,XuYunnan/go,ObjectiveJoe/go,NichoZhang/go,GeorgiCodes/go,snowsnail/go,derekmarcotte/go,yuhengye/go,alex-zhang/go,jacobxk/go,donnel6809/go,skatsuta/go,CiscoCloud/go,jonasi/go,donnel6809/go,vanloswang/go,polyverse-security/go,xiaobodu/go,deft-code/go,jdeng/go,Stan-Lin-/go,ifagnosticism/go,dkolbly/go,XuYunnan/go,gohin/go,ifagnosticism/go,arschles/go-1,GeorgiCodes/go,kim-racktop/go,xujianhai/go,arschles/go-1,ifagnosticism/go,youprofit/go,nakedgc/go,Young55555/go,jonathanmarvens/go,rachtsingh/gogojuice,sinuos/go,jasonxiong/go,theass/go,Samurais/go,g522342435/go,stormltf/go,stormltf/go,sinuos/go,likesea/go,AALEKH/go,chinanjjohn2012/go,linux-on-ibm-z/go,suncycheng/go,theif519/go,CarterTsai/go,rachtsingh/gogojuice,monetate/go,baiyunping333/go,zouchao2010/go,4ad/go,jacobsa/go,sinuos/go,jefby/go,dpatel06/go,arschles/golang-go,baiyunping333/go,akutz/go,Samurais/go,vishsingh/go,samanalysis/go,cnbin/go,beealone/go,stormltf/go,nawawi/go,jasonxiong/go,honsiorovskyi/go,dafyddcrosby/go,miolini/go,constantine001/go,rachtsingh/gogojuice,samanalysis/go,derekmarcotte/go,gohin/go,polyverse-security/go,linux-on-ibm-z/go,XuYunnan/go,agaurav/go,cnbin/go,Badredapple/go,codestation/go,linux-on-ibm-z/go,sosop/go,arschles/go-1,g522342435/go,NichoZhang/go,polyverse-security/go,CiscoCloud/go,ericsnowcurrently/go,roth1002/go,constantine001/go,derekmarcotte/go,yuhengye/go,cnbin/go,wangfakang/go-1,cookerzhu/go,agaurav/go,goodlang/good,vsdutka/go,xujianhai/go,ericsnowcurrently/go,Stan-Lin-/go,AALEKH/go,dkolbly/go,CAFxX/go,WIZARD-CXY/go,monetate/go,WIZARD-CXY/go,Young55555/go,JioCloud/go,theass/go,shines77/go,gdey/go,Endika/go,likesea/go,xinhuang327/go,rentongzhang/go,jmptrader/go,leeric92/go,jacobsa/go,theass/go,vsekhar/elastic-go,dpatel06/go,ichu501/go,sinuos/go,RBEGamer/go,miolini/go,slavau/go,shazow/go,dgnorton/go,dafyddcrosby/go,nakedgc/go,jasonxiong/go,vsekhar/elastic-go,Stan-Lin-/go,vsdutka/go,gdey/go,jdhenke/go,honsiorovskyi/go,qskycolor/go,Pulgafree/go,jefby/go,NichoZhang/go,4ad/go,Charlesdong/go-1,springning/go,Endika/go,greyhwndz/go,beealone/go,gohin/go,kevinc0825/go,Badredapple/go,linux-on-ibm-z/go,albertjin/golang-go,Endika/go,yangzhongj/go,GeorgiCodes/go,JioCloud/go,jonahglover/go,famorted/go,qskycolor/go,zouchao2010/go,mdp/go,nakedgc/go,constantine001/go,vsdutka/go,jameskumar/go,josharian/go,zouchao2010/go,Endika/go,yuhengye/go,alex-zhang/go,Pulgafree/go,odeke-em/go,dafyddcrosby/go,CAFxX/go,dpatel06/go,skotti/go,skatsuta/go,zouchao2010/go,xiaobodu/go,kevinc0825/go,skotti/go,binarycrusader/go,zcwfeng/go,danycoro/go,ErikDubbelboer/go,monetate/go,vsdutka/go,4ad/go,golang/go,xiaobodu/go,dkolbly/go,andrewchambers/go,momchil-velikov/go,beealone/go,dpatel06/go,kakuhiroshi/go,jacobhaven/go,snowsnail/go,momchil-velikov/go,jonahglover/go,CiscoCloud/go,binarycrusader/go,jefby/go,cainiaocome/go,Jordanzuo/go,jdeng/go,cainiaocome/go,undergrowthlinear/go,cloudrain21/go,yasarkunduz/go,uileyar/go,mwhudson/go,cyberroadie/go,golang/go,dkolbly/go,likesea/go,jdhenke/go,b54898533/go,jacobxk/go,likesea/go,uileyar/go,Jordanzuo/go,NunoEdgarGub1/go,4ad/go,g522342435/go,malvira/go,willjunspecial/go,jacobsa/go,dafyddcrosby/go,GeorgiCodes/go,RBEGamer/go,parkdy/go,deft-code/go,joshsammut/go,ObjectiveJoe/go,CiscoCloud/go,myPublicGit/go,wangfakang/go-1,NunoEdgarGub1/go,jefby/go,Charlesdong/go-1,beealone/go,Cofyc/go,Badredapple/go,beealone/go,vishsingh/go,lihuanghai/go,miolini/go,gdey/go,shines77/go,mdp/go,myPublicGit/go,cyberroadie/go,danycoro/go,akutz/go,undergrowthlinear/go,jacobxk/go,mwhudson/go,dkolbly/go,ganboing/go-esx,joshsammut/go,kim-racktop/go,Pulgafree/go,danycoro/go,jmptrader/go,springning/go,jonahglover/go,theif519/go,fjballest/golang,rentongzhang/go,constantine001/go,gdey/go,josharian/go,sosop/go,willjunspecial/go,likesea/go,CarterTsai/go,yangzhongj/go,mikekap/go,Stan-Lin-/go,jameskumar/go,sosop/go,gohin/go,fjballest/golang,andrewchambers/go,undergrowthlinear/go,jefby/go,devpadawan/go,zhangg/go,momchil-velikov/go,roth1002/go,ichu501/go,g522342435/go,lihuanghai/go,ImJasonH/go,ericsnowcurrently/go,kevinc0825/go,sndnvaps/go,beealone/go,cookerzhu/go,dafyddcrosby/go,cloudrain21/go,mikekap/go,jmptrader/go,cookerzhu/go,deft-code/go,greyhwndz/go,alex-zhang/go,Charlesdong/go-1,Badredapple/go,kakuhiroshi/go,roth1002/go,g522342435/go,shazow/go,momchil-velikov/go,rachtsingh/gogojuice,binarycrusader/go,Stan-Lin-/go,jmptrader/go,snowsnail/go,qskycolor/go,vsekhar/elastic-go,famorted/go,pgmreddy/go,wangfakang/go-1,snowsnail/go,likesea/go,xiuzhifu/go,deft-code/go,binarycrusader/go,XuYunnan/go,miolini/go,springning/go,CodyGuo/go,alash3al/go,albertjin/golang-go,xujianhai/go,sosop/go,youprofit/go,theass/go,josharian/go,jacobhaven/go,roth1002/go,roth1002/go,derekmarcotte/go,albertjin/golang-go,arschles/go-1,vanloswang/go,NichoZhang/go,leeric92/go,leeric92/go,shazow/go,qskycolor/go,samanalysis/go,skatsuta/go,xujianhai/go,derekmarcotte/go,goodlang/good,goodlang/good,Jordanzuo/go,CarterTsai/go,ichu501/go,malvira/go,jdeng/go,cyberroadie/go,qskycolor/go,miolini/go,danielsoro/go,vsdutka/go,myPublicGit/go,josharian/go,ErikDubbelboer/go,kakuhiroshi/go,suncycheng/go,famorted/go,myPublicGit/go,4ad/go,odeke-em/go,Endika/go,CAFxX/go,lihuanghai/go,binarycrusader/go,alash3al/go,devpadawan/go,joshsammut/go,ifagnosticism/go,gdey/go,deft-code/go,XuYunnan/go,dafyddcrosby/go,odeke-em/go,GeorgiCodes/go,devpadawan/go,pgmreddy/go,rachtsingh/gogojuice,parkdy/go,jonathanmarvens/go,agaurav/go,malvira/go,vishsingh/go,undergrowthlinear/go,dterei/go,golang/go,mikekap/go,gdey/go,xiuzhifu/go,agaurav/go,NunoEdgarGub1/go,alash3al/go,constantine001/go,skotti/go,gohin/go,dterei/go,nakedgc/go,josharian/go,cloudflare/go,shazow/go,rentongzhang/go,josharian/go,beealone/go,alex-zhang/go,cainiaocome/go,ImJasonH/go,ImJasonH/go,likesea/go,jacobxk/go,famorted/go,Samurais/go,ichu501/go,greyhwndz/go,shines77/go,alex-zhang/go,myPublicGit/go,dgnorton/go,malvira/go,dterei/go,jonasi/go,samanalysis/go,cyberroadie/go,polyverse-security/go,JioCloud/go,roth1002/go,slavau/go,mbrukman/go,Cofyc/go,b54898533/go,Young55555/go,kim-racktop/go,odeke-em/go,chinanjjohn2012/go,kim-racktop/go,jonasi/go,Samurais/go,slavau/go,alex-zhang/go,NunoEdgarGub1/go,xiaobodu/go,kevinc0825/go,vanloswang/go,albertjin/golang-go,monetate/go,vsdutka/go,CiscoCloud/go,Jordanzuo/go,dpatel06/go,ichu501/go,jacobhaven/go,CAFxX/go,WIZARD-CXY/go,alash3al/go,yuhengye/go,sndnvaps/go,albertjin/golang-go,mbrukman/go,greyhwndz/go,akutz/go,skatsuta/go,cloudrain21/go,binarycrusader/go,golang/go,Charlesdong/go-1,mgyenik/go,yangzhongj/go,CAFxX/go,danielsoro/go,xiuzhifu/go,ImJasonH/go,andrewchambers/go,xinhuang327/go,Stan-Lin-/go,devpadawan/go,vanloswang/go,fjballest/golang,AALEKH/go,ImJasonH/go,chinanjjohn2012/go,NichoZhang/go,andrewchambers/go,cookerzhu/go,WIZARD-CXY/go,jonathanmarvens/go,vanloswang/go,CarterTsai/go,joshsammut/go,constantine001/go,sndnvaps/go,lihuanghai/go,undergrowthlinear/go,CodyGuo/go,mbrukman/go,zhangg/go,jefby/go,ericsnowcurrently/go,CAFxX/go,monetate/go,parkdy/go,kevinc0825/go,momchil-velikov/go,jasonxiong/go,NunoEdgarGub1/go