filecheck fix: we need to check buffered gcodes after finding end of gcode file

Firmware/Marlin_main.cpp

@@ -1952,7 +1952,7 @@ static float probe_pt(float x, float y, float z_before) {
 bool check_commands() {
 	  bool end_command_found = false;
 
-	  if (buflen)
+	  while (buflen)
 	  {
 		  if ((code_seen("M84")) || (code_seen("M 84"))) end_command_found = true;
 		  if (!cmdbuffer_front_already_processed)

Firmware/ultralcd.cpp

@@ -5779,7 +5779,6 @@ static bool check_file(const char* filename) {
 		get_command();
 		result = check_commands();
 	}
-	cmdqueue_reset();
 	card.printingHasFinished();
 	strncpy_P(lcd_status_message, WELCOME_MSG, LCD_WIDTH);
 	return result;