In preparation for matrix attribute aliasing support, where
CalculateAliasingAttributes would get a bit more complex.

This change adds a fast-check function to determine if there is any
aliasing at all.

Bug: angleproject:4249
Change-Id: Ib2aa08b2da29a194baa905ba8f9aa2cdef0ae2c5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2488127Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Charlie Lao <cclao@google.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>