patch 8.1.2224: cannot build Amiga version

Problem:    Cannot build Amiga version.
Solution:   Add dummy mch_setmouse(). (Ola Söder, closes #5126)

Author: brammool

src/os_amiga.c

@@ -658,6 +658,12 @@ mch_can_restore_icon(void)
 }
 #endif
 
+    void
+mch_setmouse(int on UNUSED)
+{
+    // TODO: implement
+}
+
 /*
  * Insert user name in s[len].
  */

src/proto/os_amiga.pro

@@ -15,6 +15,7 @@ void mch_settitle(char_u *title, char_u *icon);
 void mch_restore_title(int which);
 int mch_can_restore_title(void);
 int mch_can_restore_icon(void);
+void mch_setmouse(int on);
 int mch_get_user_name(char_u *s, int len);
 void mch_get_host_name(char_u *s, int len);
 long mch_get_pid(void);

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2224,
 /**/
     2223,
 /**/