[dev.typeparams] internal/buildcfg: allow regabi GOEXPERIMENTs on ARM64
[dev.typeparams] internal/buildcfg: allow regabi GOEXPERIMENTs on ARM64

It is not working yet, but allow enabling the experiments so we
can develop.

Change-Id: I957eb05acb4d80b2858ff1f8c16bbfb24e0f6e56
Reviewed-on: https://go-review.googlesource.com/c/go/+/323933
Trust: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Run-TryBot: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: David Chase <ae171625adc8645b8b79b7e405a6da5aba5341e0@google.com>

golang/go,cloudflare/go,cloudflare/go,golang/go,nawawi/go,cloudflare/go,CAFxX/go,golang/go,nawawi/go,CAFxX/go,CAFxX/go,golang/go,golang/go,CAFxX/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,cloudflare/go,cloudflare/go,cloudflare/go,nawawi/go,nawawi/go,nawawi/go,nawawi/go,golang/go,golang/go,CAFxX/go,cloudflare/go,nawawi/go,CAFxX/go,golang/go