Slight size reduction by adding idle()

Marlin/planner.cpp

@@ -478,11 +478,7 @@ float junction_deviation = 0.1;
 
   // If the buffer is full: good! That means we are well ahead of the robot. 
   // Rest here until there is room in the buffer.
-  while(block_buffer_tail == next_buffer_head) {
-    manage_heater(); 
-    manage_inactivity(); 
-    lcd_update();
-  }
+  while (block_buffer_tail == next_buffer_head) idle();
 
   #ifdef MESH_BED_LEVELING
     if (mbl.active) z += mbl.get_z(x, y);