[clang] [llvm] [SystemZ] Add support for __builtin_setjmp and __builtin_longjmp (PR #116642)

[Ulrich Weigand via cfe-commits]

https://github.com/uweigand commented:

Thanks for the contribution!   Please find a number of comments inline.  Also, you should address the issues found by the CI, e.g. about coding style.

https://github.com/llvm/llvm-project/pull/116642