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

[Anton Korobeynikov via llvm-commits]

asl 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.

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