Fix build error when Automatic Mouse Layer is enabled (#22229)

quantum/pointing_device/pointing_device_auto_mouse.c

@@ -17,6 +17,7 @@
 
 #ifdef POINTING_DEVICE_AUTO_MOUSE_ENABLE
 
+#    include <string.h>
 #    include "pointing_device_auto_mouse.h"
 #    include "debug.h"
 #    include "action_util.h"