Remove the stub support we had for UNION JOIN; per discussion, this is

not likely ever to be implemented seeing it's been removed from SQL2003.
This allows getting rid of the 'filter' version of yylex() that we had in
parser.c, which should save at least a few microseconds in parsing.

src/backend/parser/scan.l

@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.131 2006/03/06 19:49:20 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.132 2006/03/07 01:00:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,8 +45,6 @@
 #undef fprintf
 #define fprintf(file, fmt, msg)  ereport(ERROR, (errmsg_internal("%s", msg)))
 
-extern YYSTYPE yylval;
-
 static int		xcdepth = 0;	/* depth of nesting in slash-star comments */
 static char    *dolqstart;      /* current $foo$ quote start string */