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

unittests/Support/ErrorOrTest.cpp

@@ -28,7 +28,9 @@ TEST(ErrorOr, SimpleValue) {
   a = t2();
   EXPECT_FALSE(a);
   EXPECT_EQ(errc::invalid_argument, a);
+#ifdef EXPECT_DEBUG_DEATH
   EXPECT_DEBUG_DEATH(*a, "Cannot get value when an error exists");
+#endif
 }
 
 #if LLVM_HAS_CXX11_STDLIB