NOOP macro for do-nothing macros

Marlin/macros.h

 #define PENDING(NOW,SOON) ((long)(NOW-(SOON))<0)
 #define ELAPSED(NOW,SOON) (!PENDING(NOW,SOON))
 
+#define NOOP do{}while(0)
+
 #endif //__MACROS_H

Marlin/ultralcd.h

   FORCE_INLINE void lcd_reset_alert_level() {}
   FORCE_INLINE bool lcd_detected(void) { return true; }
 
-  #define LCD_MESSAGEPGM(x) do{}while(0)
-  #define LCD_ALERTMESSAGEPGM(x) do{}while(0)
+  #define LCD_MESSAGEPGM(x) NOOP
+  #define LCD_ALERTMESSAGEPGM(x) NOOP
 
 #endif //ULTRA_LCD