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

toolkit/components/url-classifier/Entries.h

@@ -299,4 +299,5 @@ WriteTArray(nsIOutputStream* aStream, nsTArray_Impl<T, Alloc>& aArray)
 
 } // namespace safebrowsing
 } // namespace mozilla
+
 #endif // SBEntries_h__