Bug 40777: Create a Go bootstrap project

Merge Info

Related Issues

• #40777 (closed)

Backport Timeline

• Immediate - patchsets for critical bug fixes or other major blocker (e.g. fixes for a 0-day exploit) OR patchsets with trivial changes which do not need testing (e.g. fixes for typos or fixes easily verified in a local developer build)
• Next Minor Stable Release - patchset that needs to be verified in nightly before backport
• Eventually - patchset that needs to be verified in alpha before backport
• No Backport - patchset for the next major stable

Issue Tracking

• Link resolved issues with appropriate Release Prep issue for changelog generation

Change Description

We've talked about getting a Go bootstrap project for a while now.

The last changes on the dependency management inspired me to finally do it.

Also, the new target_replace option is very useful to build the bootstrapper only for Linux.

Please notice that the old Go project didn't use the custom GCC we build, so I continued not doing so.
The reason was probably that the original Go 1.4 didn't play well with more recent compilers, but I switched to a revised 1.4 that has been updated just for bootstrapping (see Go's doc).
So, we could switch to our compiler, if we think it's better.