Split 'BufFile' routines out of fd.c into a new module, buffile.c. Extend

BufFile so that it handles multi-segment temporary files transparently.
This allows sorts and hashes to work with data exceeding 2Gig (or whatever
the local limit on file size is).  Change psort.c to use relative seeks
instead of absolute seeks for backwards scanning, so that it won't fail
when the data volume exceeds 2Gig.

src/backend/storage/large_object/inv_api.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.59 1999/09/18 19:07:32 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.60 1999/10/13 15:02:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -300,6 +300,21 @@ inv_destroy(Oid lobjId)
  *		end of relations.  Once clustering works, we should fix this.
  */
 #ifdef NOT_USED
+
+struct pgstat
+{								/* just the fields we need from stat
+								 * structure */
+	int			st_ino;
+	int			st_mode;
+	unsigned int st_size;
+	unsigned int st_sizehigh;	/* high order bits */
+/* 2^64 == 1.8 x 10^20 bytes */
+	int			st_uid;
+	int			st_atime_s;		/* just the seconds */
+	int			st_mtime_s;		/* since SysV and the new BSD both have */
+	int			st_ctime_s;		/* usec fields.. */
+};
+
 int
 inv_stat(LargeObjectDesc *obj_desc, struct pgstat * stbuf)
 {