IR: Cleanup after test to silence ASAN builds

llvm-svn: 367758
diff --git a/llvm/unittests/IR/AsmWriterTest.cpp b/llvm/unittests/IR/AsmWriterTest.cpp
index a9d761d..4fa1889 100644
--- a/llvm/unittests/IR/AsmWriterTest.cpp
+++ b/llvm/unittests/IR/AsmWriterTest.cpp
@@ -44,6 +44,7 @@
   raw_string_ostream OS(S);
   Arg->print(OS);
   EXPECT_EQ(S, "i32 <badref>");
+  delete Arg;
 }
 
 TEST(AsmWriterTest, DumpDIExpression) {