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

[Ulrich Weigand via cfe-commits]

uweigand wrote:

Hi @anoopkg6 , I had to revert this again as it was causing a number of issues:

- An unused variable warning fixed here: https://github.com/llvm/llvm-project/commit/3c47e63723b1aa9e76f30fc8d1acef9caf4ea783
- The fuchsia build bot failure - I'm not completely sure what causes this, but it suspect the problem is that you should be using `%clang_cc1` instead of `%clang` (which would be a better idea anyway)
- The expensive checks build bot failure - this indicated a real bug the generated MI, which you can reproduce by adding `-verify-machineinstrs` to the test case (it would be a good idea to add this to those tests anyway!)

You'll have to open a new PR with a patch including those fixes.

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