With recent pragma invariant(all) fix the pragma_vertex test is failing
on MAC so excluding it from testing.

Bug: angleproject:3285
Bug: angleproject:3433
Bug: angleproject:3434
Change-Id: I59079afdbef2d23a593fe0fe061997624fea5cde
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1601364
Commit-Queue: Tobin Ehlis <tobine@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>