Golang build: amd64 builders don't support SHA extensions

The amd64 builders don't support the SHA x86-64 extensions, so our crypto/sha256 assembly is untested, in violation of the Assembly Policy.

/cc @golang/security @golang/release

Comment From: gopherbot

Change https://go.dev/cl/614656 mentions this issue: crypto/sha256,crypto/sha512: test fallback implementations

Comment From: gabyhelp

Related Issues and Documentation

• build: arm64 builders don't support SHA-512 extensions #69593

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Comment From: FiloSottile

@dr2chase not sure why this and #69593 are assigned to me? I think the next step is for @golang/release to figure out if we can select builders with more recent CPUs so we can test this code.

Comment From: rolandshoemaker

The C3D, N2D instances, based on AMD EYPC, should have these instructions.