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

[Ulrich Weigand via cfe-commits]

https://github.com/uweigand commented:

This now looks good to me (see one inline comment).   The only part missing is the doc change as discussed above - can you add this to the PR here?  Then it should be good to go.  Thanks!

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