Delete unused and long-dead header file.

src/include/utils/rel2.h

-/*-------------------------------------------------------------------------
- *
- * rel2.h
- *
- *
- *
- * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * $Id: rel2.h,v 1.10 2000/01/26 05:58:38 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
-#ifndef TMP_REL2_H
-#define TMP_REL2_H
-
-#include "utils/rel.h"
-
-extern IndexStrategy RelationGetIndexStrategy(Relation relation);
-
-extern void RelationSetIndexSupport(Relation relation, IndexStrategy strategy,
-						RegProcedure *support);
-
-#endif	 /* TMP_REL2_H */