[clang] [clang-tools-extra] [Clang] Add support for the C `defer` TS (PR #162848)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Code generally looks good to me, but this still needs some dedicated review for CodeGen. I did find a testing bug though.

https://github.com/llvm/llvm-project/pull/162848