Move M113 to cpp

Marlin/src/Marlin.cpp

   return false;
 }
 
-#if ENABLED(HOST_KEEPALIVE_FEATURE)
-  #include "gcode/host/M113.h"
-#endif
-
 #if ENABLED(BARICUDA)
   #if HAS_HEATER_1
     #include "gcode/feature/baricuda/M126.h"

Marlin/src/gcode/gcode.cpp

 extern void gcode_M85();
 extern void gcode_M92();
 extern void gcode_M100();
-extern void gcode_M113();
 extern void gcode_M114();
 extern void gcode_M115();
 extern void gcode_M117();
       #endif
 
       #if ENABLED(HOST_KEEPALIVE_FEATURE)
-        case 113: // M113: Set Host Keepalive interval
-          gcode_M113();
-          break;
+        case 113: M113(); break; // M113: Set Host Keepalive interval
       #endif
 
       #if HAS_HEATER_BED && HAS_TEMP_BED

Marlin/src/gcode/host/M113.h → Marlin/src/gcode/host/M113.cpp

  *
  */
 
+#include "../../inc/MarlinConfig.h"
+
+#if ENABLED(HOST_KEEPALIVE_FEATURE)
+
+#include "../gcode.h"
+
 /**
  * M113: Get or set Host Keepalive interval (0 to disable)
  *
  *   S<seconds> Optional. Set the keepalive interval.
  */
-void gcode_M113() {
+void GcodeSuite::M113() {
   if (parser.seenval('S')) {
-    gcode.host_keepalive_interval = parser.value_byte();
-    NOMORE(gcode.host_keepalive_interval, 60);
+    host_keepalive_interval = parser.value_byte();
+    NOMORE(host_keepalive_interval, 60);
   }
   else {
     SERIAL_ECHO_START();
-    SERIAL_ECHOLNPAIR("M113 S", (unsigned long)gcode.host_keepalive_interval);
+    SERIAL_ECHOLNPAIR("M113 S", (unsigned long)host_keepalive_interval);
   }
 }
+
+#endif // HOST_KEEPALIVE_FEATURE