[clang] [clang][CodeGen] Propagate pragma set fast-math flags to floating point builtins (PR #90377)

[Andy Kaylor via cfe-commits]

https://github.com/andykaylor approved this pull request.

This looks right to me, but @zahiraam is more familiar with this code than I am. Zahira, do you have any comments?

https://github.com/llvm/llvm-project/pull/90377