Fix conflict on rebase of GIS functions to main branch

Author: DaveGosselin-MariaDB

sql/item_sum.cc

@@ -3543,7 +3543,7 @@ Item_sum_str::fix_fields(THD *thd, Item **ref)
  /* We should ignore FIELD's in arguments to sum functions */
  with_flags|= (args[i]->with_flags & ~item_with_t::FIELD);
 if (args[i]->check_type_can_return_str(
-  Item_func_group_concat::func_name_cstring()))
+ func_name_cstring()))
  return true;
  }