Move G12 to cpp

Marlin/src/Marlin.cpp

  ***************** GCode Handlers *****************
  **************************************************/
 
-#if ENABLED(NOZZLE_CLEAN_FEATURE)
-  #include "gcode/feature/clean/G12.h"
-#endif
-
 #if ENABLED(CNC_WORKSPACE_PLANES)
   #include "gcode/geometry/G17-G19.h"
 #endif

Marlin/src/gcode/feature/clean/G12.h → Marlin/src/gcode/feature/clean/G12.cpp

  *
  */
 
+#include "../../../inc/MarlinConfig.h"
+
+#if ENABLED(NOZZLE_CLEAN_FEATURE)
+
+#include "../../../libs/nozzle.h"
+
+#include "../../gcode.h"
+#include "../../parser.h"
+#include "../../../module/motion.h"
+
 /**
  * G12: Clean the nozzle
  */
-void gcode_G12() {
+void GcodeSuite::G12() {
   // Don't allow nozzle cleaning without homing first
   if (axis_unhomed_error()) return;
 
 
   Nozzle::clean(pattern, strokes, radius, objects);
 }
+
+#endif // NOZZLE_CLEAN_FEATURE

Marlin/src/gcode/gcode.cpp

 //
 // Placeholders for non-migrated codes
 //
-extern void gcode_G12();
 extern void gcode_G17();
 extern void gcode_G18();
 extern void gcode_G19();
 
       #if ENABLED(NOZZLE_CLEAN_FEATURE)
         case 12:
-          gcode_G12(); // G12: Nozzle Clean
+          G12(); // G12: Nozzle Clean
           break;
       #endif // NOZZLE_CLEAN_FEATURE