runtime: handle linux/arm64 signal register

Set sigpc and implement dumpregs for linux/arm64.
Without this change, cmd/vet tool test will fail randomly.

Updates golang/go#20931

Change-Id: Ida07dcec46a78f9fc719c33258b5dbc4622484fc
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/220543
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed