[clang] [CIR] Add math and builtin intrinsics support (PR #175233)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

@adams381 You didn't address the comments from my most recent review. Most importantly, you need an `errorNYI` call below `Builtin::BI_setjmp` to avoid an unintended fall through.

https://github.com/llvm/llvm-project/pull/175233