X11: Allow toggling mouse_support off

Prevents accidental mouse clicks on the map.

win/X11/winX.c

@@ -1307,6 +1307,7 @@ char **argv;
 
     /* add another option that can be set */
     set_wc_option_mod_status(WC_TILED_MAP, SET_IN_GAME);
+    set_option_mod_status("mouse_support", SET_IN_GAME);
 
     load_default_resources(); /* create default_resource_data[] */
 

win/X11/winmap.c

@@ -1029,6 +1029,9 @@ Cardinal *num_params;
 
     switch (event->type) {
     case ButtonPress:
+        if (!iflags.wc_mouse_support)
+            return;
+
         button = (XButtonEvent *) event;
 #ifdef VERBOSE_INPUT
         printf("button press\n");