runtime/debug: skip TestPanicOnFault on netbsd/arm

This test has been failing since the builder was updated to
NetBSD 9. While the issue is under investigation, skip the test
so that we do not miss other breakage.

Update issue #45026

Change-Id: Id083901c517f3f88e6b4bc2b51208f65170d47a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/335909


Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>