Fix (harmless) memory leak found by memcheck.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95862 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/ADT/StringMapTest.cpp

@@ -191,6 +191,7 @@ TEST_F(StringMapTest, StringMapEntryTest) {
           testKeyFirst, testKeyFirst + testKeyLength, 1u);
   EXPECT_STREQ(testKey, entry->first());
   EXPECT_EQ(1u, entry->second);
+  free(entry);
 }
 
 // Test insert() method.