Add support for GCC compatible builtin setjmp and longjmp intrinsics. This is

Add support for GCC compatible builtin setjmp and longjmp intrinsics. This is
a supporting preliminary patch for GCC-compatible SjLJ exception handling. Note that these intrinsics are not designed to be invoked directly by the user, but
rather used by the front-end as target hooks for exception handling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71610 91177308-0d34-0410-b5e6-96231b3b80d8