cmd/link: add LC_VERSION_MIN_MACOSX to linkmode=internal OS X binaries
cmd/link: add LC_VERSION_MIN_MACOSX to linkmode=internal OS X binaries

This makes lldb willing to debug them.
The minimum version is hard-coded at OS X 10.7,
because that is the minimum that Go requires.
For more control over the version, users can
use linkmode=external and pass the relevant flags to the host linker.

Fixes #12941.

Change-Id: I20027be8aa034d07dd2a3326828f75170afe905f
Reviewed-on: https://go-review.googlesource.com/18588
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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