[llvm] [Support][APint] Add fast path for APInt::urem if RHS is power of 2 (PR #189245)

[Max Graey via llvm-commits]

MaxGraey wrote:

Yes, those tests weren't quite accurate, and pretty redundant based on existing tests. Furthermore, these cases are covered quite well by non-unit tests like filecheck tests triggered during the one failed commit. But if you think additional unit tests are necessary here, I can easily add unit tests.

https://github.com/llvm/llvm-project/pull/189245