row_build_index_entry(): Declare variables in the beginning of a block,

to comply with ISO/IEC 9899:1989.  This error was made in r834.  (Bug #22575)

row/row0row.c

@@ -131,8 +131,9 @@ row_build_index_entry(
 	}
 
 	for (i = 0; i < entry_len; i++) {
+		const dict_col_t*	col;
 		ind_field = dict_index_get_nth_field(index, i);
-		const dict_col_t*	col = ind_field->col;
+		col = ind_field->col;
 
 		dfield = dtuple_get_nth_field(entry, i);