Explicitly mark overriding destructors as "virtual"

It appears that the C++ standard allows overriding destructors to be marked
"override," but at least some MSVC versions complain about it, so at least make
sure such destructors are explicitly marked "virtual."

Change-Id: I0e1cafa7584fd16ebdce61f569eae2373a71b0a1

dbaccess/source/core/dataaccess/databaseregistrations.cxx

@@ -78,7 +78,7 @@ namespace dbaccess
         DatabaseRegistrations( const Reference<XComponentContext>& _rxContext );
 
     protected:
-        ~DatabaseRegistrations();
+        virtual ~DatabaseRegistrations();
 
     public:
         virtual ::sal_Bool SAL_CALL hasRegisteredDatabase( const OUString& _Name ) throw (IllegalArgumentException, RuntimeException, std::exception) SAL_OVERRIDE;