tests: Reimplement the bituniontest as a googletest.

The implementation is very similar to the old test structurally, and
should test all the same things.

Change-Id: I58f1559d0943f2494ef06ee1d7ee5314a3852a8c
Reviewed-on: https://gem5-review.googlesource.com/6085
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2 files changed