cmd/dist: skip internal linking tests on arm64

The previous workaround for issue #39466 only disabled this test for
Linux. However, the issue manifests for all arm64 systems with gcc 9.4
and above. The new netbsd-arm64 builder uses NetBSD-current with gcc
10.3, so it fails in the same way.

Updates #39466

Change-Id: I276a99a5e60914e5c22f74a680e461bea17cfe92
Reviewed-on: https://go-review.googlesource.com/c/go/+/383554


Trust: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>