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

[Ulrich Weigand via cfe-commits]

https://github.com/uweigand commented:

I think we're getting close now - but I still have a few comments below.  Thanks!

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