Bug 1182996 - Fix and add missing namespace comments. rs=ehsan

The bulk of this commit was generated by running:

  run-clang-tidy.py \
    -checks='-*,llvm-namespace-comment' \
    -header-filter=^/.../mozilla-central/.* \
    -fix

xpcom/glue/nsThreadUtils.cpp

@@ -304,7 +304,7 @@ nsNameThreadRunnable::Run()
   return NS_OK;
 }
 
-} // anonymous namespace
+} // namespace
 
 void
 NS_SetThreadName(nsIThread* aThread, const nsACString& aName)