[clang] [clang][NFC] Specify Type and ExtQuals as having 16-byte alignment (PR #68377)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

LGTM! If @zygoloid (or others) have concerns, we can revert and address them post-commit.

https://github.com/llvm/llvm-project/pull/68377