Now that the lowerinvoke pass inserts calls to llvm.setjmp/llvm.longjmp, some

Now that the lowerinvoke pass inserts calls to llvm.setjmp/llvm.longjmp, some
hacks can be banished.  Also, this gives us the opportunity to emit special code
for the setjmp/longjmps which alows the elimination of one GCC warning for every
setjmp/longjmp site (which is often THOUSANDS in C++ programs).  Yaay!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11484 91177308-0d34-0410-b5e6-96231b3b80d8