Add #ifndef NDEBUG markers around EXPECT_DEATH after r267270

http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/36076

llvm-svn: 267275
diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index 424b7be..71c5dd4 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -2341,6 +2341,7 @@
   DistinctMDOperandPlaceholder(7).replaceUseWith(MDTuple::get(Context, None));
 }
 
+#ifndef NDEBUG
 #ifdef GTEST_HAS_DEATH_TEST
 TEST_F(DistinctMDOperandPlaceholderTest, MetadataAsValue) {
   // This shouldn't crash.
@@ -2383,5 +2384,6 @@
   }
 }
 #endif
+#endif
 
 } // end namespace