Patch bootstrap clang with prebuilt arm64 universal libs

We need arm64 version of libclang_rt and libc++ to bootstrap stage1
compiler-rt runtimes build. Patch bootstrap clang with libclang_rt.osx
and libc++ built locally with Xcode toolchain.

Verified this does not change 2-stage output of x86_64 part of the
universal build result.

Bug: 173856309
Test: build universal Android LLVM on x86 and M1 Mac
Change-Id: Ic515d1d68fcc86e21c65ba2fff06930eb19c0a55
3 files changed