[gardening] C++ gardening: Terminate namespaces, fix argument names, ...

Changes:
* Terminate all namespaces with the correct closing comment.
* Make sure argument names in comments match the corresponding parameter name.
* Remove redundant get() calls on smart pointers.
* Prefer using "override" or "final" instead of "virtual". Remove "virtual" where appropriate.

lib/SILOptimizer/LoopTransforms/ArrayBoundsCheckOpts.cpp

@@ -1397,7 +1397,7 @@ public:
     }
   }
 };
-}
+} // end anonymous namespace
 
 SILTransform *swift::createABCOpt() {
   return new ABCOpt();