__builtin.Sql.Connection: Improved field fetching in res_obj_to_array().

Some SQL drivers do not support fetching the set of field names
before the first call of fetch_row(), and/or after the last
such call.

Note: Also switches to using fetch_row() instead of fetch_row_array()
to avoid the above issue.

Fixes #10035.

lib/modules/__builtin.pmod/Sql.pmod/Connection.pike

@@ -387,10 +387,13 @@ array(mapping(string:mixed))
     if (arrayp(res_obj))
       rows = res_obj;
     else {
-      fields = 0;
+      fields = res_obj->fetch_fields();
       rows = ({});
-      while (row = res_obj->fetch_row_array())
-        rows += row;
+      while (row = res_obj->fetch_row()) {
+        rows += ({ row });
+	if (!fields)
+	  fields = res_obj->fetch_fields();
+      }
     }
 
     if (!fields)