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

[Alan Zhao via llvm-commits]

alanzhao1 wrote:

> > With #100483, if the inline asm version of `ptrauth_strip` is used instead of the builtin, the inline asm implementation will return an unsigned long, causing an incompatible pointer conversion issue.
> 
> To be more precise, it was inline asm version before that PR. It was just an implicit cast due to function call result.

Updated the PR description.

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