[clang] [Clang][CodeGen] Fix builtin_fpclassify with llvm.is.fpclass (PR #183430)

[Matt Arsenault via cfe-commits]

https://github.com/arsenm commented:

Seems like there's missing test coverage. There should be changes for the non-strictfp case too?

https://github.com/llvm/llvm-project/pull/183430