1. Fix XED data error for Int64x2 Greater compare, add overwrite defs.
2. Uint* equals could just use Int* equals, relaxed the defs.

This CL generates CL 686876.

Change-Id: Ib110e2547246a4e197348912c77793ab2bfc9466
Reviewed-on: https://go-review.googlesource.com/c/arch/+/686817
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>