[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/SILGen/SILGenPattern.cpp

@@ -863,7 +863,7 @@ public:
   }
 };
 
-}
+} // end anonymous namespace
 
 /// Return the dispatchable length of the given column.
 static unsigned getConstructorPrefix(const ClauseMatrix &matrix,
@@ -2075,7 +2075,7 @@ namespace {
     bool walkToTypeLocPre(TypeLoc &TL) override { return false; }
     bool walkToTypeReprPre(TypeRepr *T) override { return false; }
   };
-}
+} // end anonymous namespace
 
 
 static bool containsFallthrough(Stmt *S) {