Revert "[CMake][compiler-rt][AArch64] Avoid preprocessing LSE builtins separately"

Causing issues on Apple buildbots.
http://green.lab.llvm.org/green/job/clang-stage1-RA/17019/console

This reverts commit 33b740f8.
This reverts commit d9697c2e.

Differential Revision: https://reviews.llvm.org/D93199