[llvm] [PPC] Set minimum of largest number of comparisons to use bit test for switch lowering (PR #155910)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

Buildbot is failing with a real error.  (Not sure why it's only triggering on the aarch64 bot.)

Does this have any effect on non-PPC targets by default?  Or is MaxBitTestEntry always at least 2?

Otherwise LGTM

https://github.com/llvm/llvm-project/pull/155910