[clang] [PAC][clang] Define `PointerAuthQualifier` and `PointerAuthenticationMode` (PR #84384)

[Daniil Kovalev via cfe-commits]

kovdan01 wrote:

I've left 4 commits to distinguish code coming from different sources during
review. Here is the origin of the code for each of the commits:

- ef23d427b48687b62da9e1062886ddfcc1649b6a: https://github.com/apple/llvm-project/commit/a94321f13043a39b02fa7106b8270767651354cd
- 9e296a1a69158419960c265f12f52523db0c8e2a: https://github.com/ahmedbougacha/llvm-project/commit/017eede69b9b06ff432e6f817e046723cf3207f0
- 80c27eef1352d0daa3f2eaea43499e54f093c6c1:
  - https://github.com/ahmedbougacha/llvm-project/commit/cc7ba7eb1814e9b254c7d94aa0b78cb0e21acfc5
  - https://github.com/ahmedbougacha/llvm-project/commit/c9ce0d408f1d9aeffc7b86256334220aec6de5a3
  - https://github.com/access-softek/llvm-project/pull/75
- 0b75c0a774e1e8afb56de95485acf447f11ccd6d: https://github.com/ahmedbougacha/llvm-project/commit/cc7ba7eb1814e9b254c7d94aa0b78cb0e21acfc5

Commits from @ahmedbougacha's repo are taken from the eng/arm64e-upstream-llvmorg branch.



https://github.com/llvm/llvm-project/pull/84384