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

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin commented:

Random unhinged thought: Can i put a defer statement inside a statement expression? in the initializer of a compound literal?

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