[PAC] Implement -mbranch-protection=pauthabi

[asl]

Downstream commit: access-softek/llvm-project@ff95e04

[llvmbot]

@llvm/issue-subscribers-clang-driver

Author: Anton Korobeynikov (asl)

Downstream commit: https://github.com/access-softek/llvm-project/commit/ff95e04d4d498827404e7fc30c27ea22a074871c

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Anton Korobeynikov (asl)

Downstream commit: https://github.com/access-softek/llvm-project/commit/ff95e04d4d498827404e7fc30c27ea22a074871c