runtime: lift state variables from func gc to var work
runtime: lift state variables from func gc to var work

We're about to split func gc across several functions, so lift the
local variables it uses for tracking statistics and state across the
cycle into the global "work" variable.

Change-Id: Ie955f2f1758c7f5a5543ea1f3f33b222bc4b1d37
Reviewed-on: https://go-review.googlesource.com/16353
Reviewed-by: Rick Hudson <838bd060584c511f21c75c69ea04b7b120d86af0@golang.org>
Run-TryBot: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

Samurais/go,odeke-em/go,vsekhar/elastic-go,4ad/go,mwhudson/go,suncycheng/go,kim-racktop/go,vsekhar/elastic-go,suncycheng/go,cyberroadie/go,miolini/go,sndnvaps/go,sndnvaps/go,codestation/go,goodlang/good,mwhudson/go,fjballest/golang,rachtsingh/gogojuice,derekmarcotte/go,binarycrusader/go,CAFxX/go,momchil-velikov/go,ImJasonH/go,deft-code/go,cyberroadie/go,cloudflare/go,cyberroadie/go,roth1002/go,CAFxX/go,binarycrusader/go,derekmarcotte/go,Endika/go,roth1002/go,polyverse-security/go,akutz/go,miolini/go,josharian/go,vsekhar/elastic-go,josharian/go,cyberroadie/go,nawawi/go,codestation/go,ImJasonH/go,Cofyc/go,rachtsingh/gogojuice,kim-racktop/go,CAFxX/go,deft-code/go,kim-racktop/go,Cofyc/go,josharian/go,roth1002/go,derekmarcotte/go,deft-code/go,cloudflare/go,nawawi/go,deft-code/go,theif519/go,golang/go,momchil-velikov/go,mwhudson/go,Samurais/go,Cofyc/go,Jordanzuo/go,derekmarcotte/go,fjballest/golang,josharian/go,Samurais/go,4ad/go,linux-on-ibm-z/go,suncycheng/go,miolini/go,mwhudson/go,kim-racktop/go,theif519/go,deft-code/go,Endika/go,deft-code/go,odeke-em/go,golang/go,Cofyc/go,Jordanzuo/go,mwhudson/go,sndnvaps/go,goodlang/good,binarycrusader/go,golang/go,vanloswang/go,binarycrusader/go,theif519/go,goodlang/good,Cofyc/go,deft-code/go,akutz/go,momchil-velikov/go,linux-on-ibm-z/go,codestation/go,codestation/go,nawawi/go,goodlang/good,ImJasonH/go,odeke-em/go,vanloswang/go,cyberroadie/go,vsekhar/elastic-go,Jordanzuo/go,roth1002/go,Samurais/go,goodlang/good,linux-on-ibm-z/go,rachtsingh/gogojuice,miolini/go,miolini/go,goodlang/good,cyberroadie/go,nawawi/go,CAFxX/go,4ad/go,polyverse-security/go,christopher-henderson/Go,4ad/go,ImJasonH/go,golang/go,suncycheng/go,ImJasonH/go,fjballest/golang,cyberroadie/go,momchil-velikov/go,roth1002/go,akutz/go,golang/go,golang/go,binarycrusader/go,vanloswang/go,vanloswang/go,theif519/go,CAFxX/go,Jordanzuo/go,linux-on-ibm-z/go,ganboing/go-esx,CAFxX/go,rachtsingh/gogojuice,roth1002/go,cloudflare/go,codestation/go,akutz/go,kim-racktop/go,goodlang/good,rachtsingh/gogojuice,derekmarcotte/go,goodlang/good,Endika/go,sndnvaps/go,Jordanzuo/go,ImJasonH/go,binarycrusader/go,josharian/go,suncycheng/go,sndnvaps/go,akutz/go,josharian/go,cloudflare/go,odeke-em/go,theif519/go,linux-on-ibm-z/go,ganboing/go-esx,polyverse-security/go,akutz/go,ganboing/go-esx,theif519/go,Endika/go,nawawi/go,ganboing/go-esx,polyverse-security/go,roth1002/go,Samurais/go,Endika/go,momchil-velikov/go,4ad/go,momchil-velikov/go,miolini/go,theif519/go,vanloswang/go,golang/go,polyverse-security/go,fjballest/golang,derekmarcotte/go,mwhudson/go,deft-code/go,ImJasonH/go,ImJasonH/go,ganboing/go-esx,vsekhar/elastic-go,nawawi/go,vsekhar/elastic-go,binarycrusader/go,derekmarcotte/go,fjballest/golang,suncycheng/go,4ad/go,Jordanzuo/go,ganboing/go-esx,Samurais/go,fjballest/golang,odeke-em/go,rachtsingh/gogojuice,cyberroadie/go,Samurais/go,vsekhar/elastic-go,momchil-velikov/go,polyverse-security/go,akutz/go,kim-racktop/go,Endika/go,josharian/go,rachtsingh/gogojuice,Endika/go,4ad/go,vanloswang/go,josharian/go,CAFxX/go,suncycheng/go,nawawi/go,golang/go,momchil-velikov/go,Jordanzuo/go,cloudflare/go,mwhudson/go,derekmarcotte/go,odeke-em/go,vanloswang/go,cloudflare/go,Cofyc/go,4ad/go,binarycrusader/go,kim-racktop/go,theif519/go,sndnvaps/go,nawawi/go,vsekhar/elastic-go,fjballest/golang,fjballest/golang,sndnvaps/go,Cofyc/go,linux-on-ibm-z/go,ganboing/go-esx,akutz/go,ganboing/go-esx,polyverse-security/go,kim-racktop/go,codestation/go,codestation/go,cloudflare/go,sndnvaps/go,CAFxX/go,mwhudson/go,odeke-em/go,vanloswang/go,codestation/go,miolini/go,Endika/go,polyverse-security/go,linux-on-ibm-z/go,odeke-em/go,Samurais/go,miolini/go,suncycheng/go,linux-on-ibm-z/go,roth1002/go,cloudflare/go,rachtsingh/gogojuice,Cofyc/go,Jordanzuo/go