[clang] [clang] Remove FEM_Indeterminable (PR #137661)

[Zahira Ammarguellat via cfe-commits]

zahiraam wrote:

> Two of the fixes were to code that was removed while resolving the merge conflict on the LANG_OPT declaration, I thought with the revert of [c2a62af](https://github.com/llvm/llvm-project/commit/c2a62af2a51d58183bcd72ee8a86c37ddd526758) I got all the changes but I'll recheck

Thanks.

https://github.com/llvm/llvm-project/pull/137661