[compiler-rt] [compiler-rt][ubsan][nfc-ish] Fix a type conversion bug (PR #100665)

[Anton Korobeynikov via llvm-commits]

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

Provided that downstream builds pass. AFAIK there are no public builtbots that checks pac-ret configuration.

Thanks!

https://github.com/llvm/llvm-project/pull/100665