error: cannot use dynamic_cast with -fno-rtti

...with recent Clang trunk towards 3.4

Change-Id: Ie0991c7bd560c30551aeaada426382a889b46391

compilerplugins/clang/checkconfigmacros.cxx

@@ -49,6 +49,7 @@ class CheckConfigMacros
         virtual void Defined( const Token& macroToken, const MacroDirective* info, SourceRange Range ) override;
 #endif
 #endif
+        enum { isPPCallback = true };
     private:
         void checkMacro( const Token& macroToken, SourceLocation location );
         std::set< string > configMacros;