Move M18_M84, M85 to cpp

Marlin/src/Marlin.cpp

 #endif
 
 // Inactivity shutdown
-static millis_t max_inactive_time = 0;
-static millis_t stepper_inactive_time = (DEFAULT_STEPPER_DEACTIVE_TIME) * 1000UL;
+millis_t max_inactive_time = 0,
+         stepper_inactive_time = (DEFAULT_STEPPER_DEACTIVE_TIME) * 1000UL;
 
 #if ENABLED(Z_DUAL_ENDSTOPS)
   float z_endstop_adj;
   return false;
 }
 
-#include "gcode/control/M18_M84.h"
-
-#include "gcode/control/M85.h"
-
 #include "gcode/config/M92.h"
 
 #if ENABLED(M100_FREE_MEMORY_WATCHER)

Marlin/src/Marlin.h

   linear_fit* lsf_linear_fit(double x[], double y[], double z[], const int);
 #endif
 
+// Inactivity shutdown timer
+extern millis_t max_inactive_time, stepper_inactive_time;
+
 #if ENABLED(Z_DUAL_ENDSTOPS)
   extern float z_endstop_adj;
 #endif

Marlin/src/gcode/control/M18_M84.h → Marlin/src/gcode/control/M18_M84.cpp

  *
  */
 
+#include "../gcode.h"
+#include "../../Marlin.h" // for stepper_inactive_time
+#include "../../module/stepper.h"
+
 #if ENABLED(AUTO_BED_LEVELING_UBL) && ENABLED(ULTRA_LCD)
-  extern bool defer_return_to_status;
+  #include "../../feature/bedlevel/bedlevel.h"
+  #include "../../lcd/ultralcd.h"
 #endif
 
 /**
  * M18, M84: Disable stepper motors
  */
-void gcode_M18_M84() {
+void GcodeSuite::M18_M84() {
   if (parser.seenval('S')) {
     stepper_inactive_time = parser.value_millis_from_seconds();
   }

Marlin/src/gcode/control/M85.h → Marlin/src/gcode/control/M85.cpp

  *
  */
 
+#include "../gcode.h"
+#include "../../Marlin.h" // for max_inactive_time
+
 /**
  * M85: Set inactivity shutdown timer with parameter S<seconds>. To disable set zero (default)
  */
-void gcode_M85() {
+void GcodeSuite::M85() {
 
   if (parser.seen('S')) max_inactive_time = parser.value_millis_from_seconds();
 
 }
-

Marlin/src/gcode/gcode.cpp

 //
 // Placeholders for non-migrated codes
 //
-extern void gcode_M18_M84();
-extern void gcode_M85();
 extern void gcode_M92();
 extern void gcode_M100();
 extern void gcode_M114();
       case 83: M83(); break;      // M83: Set E axis relative mode
 
       case 18: // M18 => M84
-      case 84: // M84: Disable all steppers or set timeout
-        gcode_M18_M84();
-        break;
-      case 85: // M85: Set inactivity stepper shutdown timeout
-        gcode_M85();
-        break;
+      case 84: M18_M84(); break;  // M84: Disable all steppers or set timeout
+      case 85: M85(); break;      // M85: Set inactivity stepper shutdown timeout
+
       case 92: // M92: Set the steps-per-unit for one or more axes
         gcode_M92();
         break;

Marlin/src/lcd/ultralcd.h

 
   #if ENABLED(ULTIPANEL)
 
+    extern bool defer_return_to_status;
+
     // Function pointer to menu functions.
     typedef void (*screenFunc_t)();