runtime: guard against array out of bounds in GoroutineProfile
runtime: guard against array out of bounds in GoroutineProfile

The previous CL is the real fix. This one is just insurance.

Fixes #14046 again.

Change-Id: I553349504bb1789e4b66c888dbe4034568918ad6
Reviewed-on: https://go-review.googlesource.com/18977
Reviewed-by: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>

ganboing/go-esx,ImJasonH/go,polyverse-security/go,vsekhar/elastic-go,binarycrusader/go,golang/go,ImJasonH/go,vanloswang/go,codestation/go,golang/go,goodlang/good,josharian/go,vanloswang/go,golang/go,derekmarcotte/go,vanloswang/go,nawawi/go,Endika/go,Endika/go,akutz/go,josharian/go,nawawi/go,ganboing/go-esx,binarycrusader/go,CAFxX/go,linux-on-ibm-z/go,codestation/go,Endika/go,nawawi/go,Endika/go,akutz/go,Cofyc/go,josharian/go,Samurais/go,Endika/go,suncycheng/go,linux-on-ibm-z/go,momchil-velikov/go,josharian/go,codestation/go,sndnvaps/go,Samurais/go,ImJasonH/go,derekmarcotte/go,Cofyc/go,CAFxX/go,suncycheng/go,akutz/go,derekmarcotte/go,4ad/go,CAFxX/go,ganboing/go-esx,miolini/go,miolini/go,goodlang/good,nawawi/go,theif519/go,golang/go,Samurais/go,cloudflare/go,suncycheng/go,sndnvaps/go,vanloswang/go,josharian/go,ImJasonH/go,binarycrusader/go,derekmarcotte/go,Endika/go,vanloswang/go,mwhudson/go,CAFxX/go,cloudflare/go,vsekhar/elastic-go,ganboing/go-esx,linux-on-ibm-z/go,goodlang/good,sndnvaps/go,sndnvaps/go,ImJasonH/go,polyverse-security/go,Endika/go,ImJasonH/go,Samurais/go,miolini/go,vsekhar/elastic-go,theif519/go,linux-on-ibm-z/go,goodlang/good,cloudflare/go,vsekhar/elastic-go,codestation/go,vsekhar/elastic-go,golang/go,golang/go,akutz/go,nawawi/go,momchil-velikov/go,suncycheng/go,binarycrusader/go,momchil-velikov/go,vsekhar/elastic-go,sndnvaps/go,polyverse-security/go,codestation/go,theif519/go,momchil-velikov/go,binarycrusader/go,4ad/go,akutz/go,momchil-velikov/go,Endika/go,akutz/go,vanloswang/go,mwhudson/go,codestation/go,mwhudson/go,Cofyc/go,golang/go,4ad/go,polyverse-security/go,momchil-velikov/go,momchil-velikov/go,nawawi/go,theif519/go,akutz/go,theif519/go,miolini/go,linux-on-ibm-z/go,polyverse-security/go,Samurais/go,4ad/go,ganboing/go-esx,akutz/go,4ad/go,Samurais/go,Cofyc/go,codestation/go,miolini/go,sndnvaps/go,cloudflare/go,4ad/go,ganboing/go-esx,Cofyc/go,CAFxX/go,goodlang/good,cloudflare/go,vanloswang/go,linux-on-ibm-z/go,theif519/go,derekmarcotte/go,sndnvaps/go,momchil-velikov/go,ImJasonH/go,cloudflare/go,miolini/go,vsekhar/elastic-go,Samurais/go,derekmarcotte/go,linux-on-ibm-z/go,josharian/go,binarycrusader/go,mwhudson/go,goodlang/good,goodlang/good,4ad/go,CAFxX/go,vsekhar/elastic-go,josharian/go,Cofyc/go,Samurais/go,suncycheng/go,binarycrusader/go,cloudflare/go,ImJasonH/go,mwhudson/go,ganboing/go-esx,vanloswang/go,CAFxX/go,4ad/go,nawawi/go,theif519/go,mwhudson/go,suncycheng/go,golang/go,mwhudson/go,Cofyc/go,derekmarcotte/go,goodlang/good,miolini/go,mwhudson/go,binarycrusader/go,polyverse-security/go,linux-on-ibm-z/go,suncycheng/go,polyverse-security/go,codestation/go,polyverse-security/go,nawawi/go,josharian/go,theif519/go,miolini/go,CAFxX/go,derekmarcotte/go,cloudflare/go,ganboing/go-esx,christopher-henderson/Go,suncycheng/go,sndnvaps/go,Cofyc/go