internal/buildcfg: make regabi enable regabiargs
internal/buildcfg: make regabi enable regabiargs

For #40724.

Change-Id: I6e9d7eb91883857479699972a974a39ce3d9d2cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/310849
Trust: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
Run-TryBot: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>

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