An interim code cleanup.

Major re-write of code yet has to be done, to circumvent
assigning of UNIT to current select and to deal better with 
offset, limit.


mysql-test/r/union.result:
  A fix of merge fix

mysql-test/r/union.result

@@ -267,4 +267,3 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	const	PRIMARY	PRIMARY	4	const	1	
 2	UNION	t1	ref	b	b	5	const	1	Using where
 drop table t1,t2;
->>>>>>>

sql/sql_parse.cc

@@ -3275,7 +3275,6 @@ mysql_new_select(LEX *lex, bool move_down)
     select_lex->include_neighbour(lex->current_select);
 
   select_lex->master_unit()->global_parameters= select_lex;
-  DBUG_ASSERT(lex->current_select->linkage != GLOBAL_OPTIONS_TYPE);
   select_lex->include_global((st_select_lex_node**)&lex->all_selects_list);
   lex->current_select= select_lex;
   return 0;

sql/sql_yacc.yy

@@ -4744,10 +4744,10 @@ optional_order_or_limit:
 	    LEX *lex= &thd->lex;
 	    DBUG_ASSERT(lex->current_select->linkage != GLOBAL_OPTIONS_TYPE);
 	    SELECT_LEX *sel= lex->current_select->select_lex();
-	    sel->master_unit()->global_parameters=
-	      sel->master_unit();
-	    lex->current_select= sel->master_unit();
-	    lex->current_select->no_table_names_allowed= 1;
+	    SELECT_LEX_UNIT *unit= sel->master_unit();
+	    unit->global_parameters= unit;
+	    unit->no_table_names_allowed= 1;
+	    lex->current_select= unit;
 	    thd->where= "global ORDER clause";
 	  }
 	order_or_limit