Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

  $ tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
      -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
      work/llvm/tools/clang

To reduce churn, not touching namespaces spanning less than 10 lines.

llvm-svn: 240270
diff --git a/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp b/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
index 9f8f6e3..7eb8e93 100644
--- a/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
+++ b/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
@@ -117,7 +117,7 @@
 
 };
 
-}
+} // namespace
 
 static FrontendPluginRegistry::Add<PrintFunctionNamesAction>
 X("print-fns", "print function names");