Remove unused include file, per ITAGAKI Takahiro. AFAICT this has been

dead code since Postgres95.

src/include/storage/itempos.h

-/*-------------------------------------------------------------------------
- *
- * itempos.h
- *	  Standard POSTGRES buffer page long item subposition definitions.
- *
- *
- * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * $PostgreSQL: pgsql/src/include/storage/itempos.h,v 1.25 2008/01/01 19:45:59 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
-#ifndef ITEMPOS_H
-#define ITEMPOS_H
-
-#include "storage/buf.h"
-#include "storage/itemid.h"
-
-typedef struct ItemSubpositionData
-{
-	Buffer		op_db;
-	ItemId		op_lpp;
-	char	   *op_cp;			/* XXX */
-	uint32		op_len;
-}	ItemSubpositionData;
-
-typedef ItemSubpositionData *ItemSubposition;
-
-/*
- *		PNOBREAK(OBJP, LEN)
- *		struct	objpos	*OBJP;
- *		unsigned		LEN;
- */
-#define PNOBREAK(OBJP, LEN)		((OBJP)->op_len >= (LEN))
-
-/*
- *		PSKIP(OBJP, LEN)
- *		struct	objpos	*OBJP;
- *		unsigned		LEN;
- */
-#define PSKIP(OBJP, LEN) \
-		do { (OBJP)->op_cp += (LEN); (OBJP)->op_len -= (LEN); } while (0)
-
-#endif   /* ITEMPOS_H */