[clang] [Clang] Consider preferred_type in bitfield warnings (#116760) (PR #116785)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

I'm using nightly builds of Clang to work on Clang, and I ended up passing `-Wno-preferred-type-bitfield-enum-conversion`, otherwise my terminal is drowned in the aforementioned warning about `FPEvalMethod`

https://github.com/llvm/llvm-project/pull/116785