[clang] [clang][codegen] Fix possible crash when setting TBAA metadata on FP math libcalls (PR #108575)

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

I've bisected breakage, on mingw x86 platforms relating to double vs long double routines, down to this commit.

I'll follow up with more details when I manage to pinpoint what changes and where, due to this change.

https://github.com/llvm/llvm-project/pull/108575