Linux/MacOSX: add progress bar for mouse collected entropy in GUI of volume creation wizard. Add mutex protection in event handler for shared counter variable

src/Main/Forms/KeyfileGeneratorDialog.h

@@ -35,6 +35,7 @@ namespace VeraCrypt
 		
 		HashList Hashes;
 		int	MouseEventsCounter;
+		Mutex AccessMutex;
 	};
 }