[libc][NFC] Workaround clang assertion in inline asm

The clobber list "cc" is added to inline assembly to workaround a clang assertion that triggers when building with a clang built with assertions enabled. See bug [53391](https://github.com/llvm/llvm-project/issues/53391).

See https://godbolt.org/z/z3bc6a9PM showing functionally same output assembly.

Reviewed By: sivachandra, lntue

Differential Revision: https://reviews.llvm.org/D118099