proposal: build: promote windows/arm64 to first class port

[dagood]

Proposal Details

We (@qmuntal, @gdams, and I--Microsoft folks) think the windows/arm64 port is at a point where it fits https://go.dev/wiki/PortingPolicy#first-class-ports and can be promoted.

Specifically: the windows/arm64 builders have been running for a while and don't seem to have unreasonable maintenance problems, and the builders are operated by the Go team.

I'm raising this proposal to see if it's time, or to find out if there's anything we can help with to get it there.

Follows up on this comment and issue:

• clarify Go support policy for secondary ports #53383 (comment)
• x/build/env/windows/arm64: add Windows arm64 builders provided by Microsoft #53541

[bcmills]

For reference, the open issues for windows/arm64:
https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3AOS-Windows+label%3Aarch-arm64

[bcmills]

• cmd/go,os: build cache checksum errors in x/tools/cmd/callgraph.TestCallgraph on windows/arm64 #50706 in particular is one I recall having discussed as a potential blocker for promoting the port to first-class.

[dagood]

This one seems like a similar kind of weird flakiness, given @qmuntal's comment about 274GB:

• x/build: "fatal error: out of memory" on windows-arm64-11 #51019 (comment)

[ianlancetaylor]

CC @golang/windows

[ianlancetaylor]

CC @golang/release

[rsc]

It would be good to have some eyes on the issues that @bcmills pointed out above.