[clang] [mlir] [CIR] Implement 'noreturn' attribute for functions/calls. (PR #177978)

[Tobias Gysi via cfe-commits]

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

Thanks for adding the tests!

The LLVM dialect changes LGTM.

https://github.com/llvm/llvm-project/pull/177978