ErrorOrTest.cpp: Check existence of EXPECT_DEBUG_DEATH. It is not always available.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173123 91177308-0d34-0410-b5e6-96231b3b80d8
This test is only supposed to test that the objc-arc alias analysis
allows for gvn to perform certain optimizations. Thus the runline should
only contain -objc-arc-aa, not the full -objc-arc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173126 91177308-0d34-0410-b5e6-96231b3b80d8