The exception handling intrinsics return values,

The exception handling intrinsics return values,
so must be lowered to a value, not nothing at all.
Subtle point: I made eh_selector return 0 and
eh_typeid_for return 1.  This means that only
cleanups (destructors) will be run as the exception
unwinds [if eh_typeid_for returned 0 then it would
be as if the first catch always matched, and the
corresponding handler would be run], which is
probably want you want in the CBE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37947 91177308-0d34-0410-b5e6-96231b3b80d8