[clang] [clang] Assert the enum FPOpts and LangOpts fit into the storage (PR #126166)

[Jan Svoboda via cfe-commits]

https://github.com/jansvoboda11 approved this pull request.

Ok, makes sense to fix the immediate problem now and follow up with the more robust fix later. Would be good if you could leave a FIXME on one of the `assert` calls in `LangOptions.h` outlining the potential improvement via `static_assert`. LGTM

https://github.com/llvm/llvm-project/pull/126166