Document end of anonymous namespaces, NFC

Prevent clang-format from deleting the preceding newline.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265227 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/IR/ValueMapTest.cpp

@@ -292,4 +292,4 @@ TYPED_TEST(ValueMapTest, SurvivesModificationByConfig) {
   EXPECT_EQ(0u, VM.count(this->AddV.get()));
 }
 
-}
+} // end namespace

unittests/Transforms/Utils/ValueMapperTest.cpp

@@ -55,4 +55,4 @@ TEST(ValueMapperTest, MapMetadataDistinctOperands) {
   EXPECT_EQ(New, D->getOperand(0));
 }
 
-}
+} // end namespace