[clang] [clang][bytecode] Yet another __builtin_constant_p implementation (PR #130143)

[Timm Baeder via cfe-commits]

tbaederr wrote:

Yeah. I think I'll merge this. The implementation isn't _that_ invasive, so if any problem arises, it's not too bad to revert it again.

https://github.com/llvm/llvm-project/pull/130143