net: make GODEBUG=netdns=cgo force cgo as documented
net: make GODEBUG=netdns=cgo force cgo as documented

It wasn't working. The wrong variable was used.

This would ideally have tests. It's also DEBUG.

Fixes #11816

Change-Id: Iec42d229b81d78cece4ba5c73f3040e2356eb98f
Reviewed-on: https://go-review.googlesource.com/12544
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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