Fix for bug #12991 (compile error --without-geometry)

myisam/mi_check.c:
  this code shouldn't be compiled without Rtree keys's support

myisam/mi_check.c

@@ -1045,9 +1045,12 @@ int chk_data_link(MI_CHECK *param, MI_INFO *info,int extend)
 	      /* We don't need to lock the key tree here as we don't allow
 		 concurrent threads when running myisamchk
 	      */
-              int search_result= (keyinfo->flag & HA_SPATIAL) ?
+              int search_result=
+#ifdef HAVE_RTREE_KEYS
+                (keyinfo->flag & HA_SPATIAL) ?
                 rtree_find_first(info, key, info->lastkey, key_length,
                                  SEARCH_SAME) : 
+#endif
                 _mi_search(info,keyinfo,info->lastkey,key_length,
                            SEARCH_SAME, info->s->state.key_root[key]);
               if (search_result)