Restructure some header files a bit, in particular heapam.h, by removing some

unnecessary #include lines in it.  Also, move some tuple routine prototypes and
macros to htup.h, which allows removal of heapam.h inclusion from some .c
files.

For this to work, a new header file access/sysattr.h needed to be created,
initially containing attribute numbers of system columns, for pg_dump usage.

While at it, make contrib ltree, intarray and hstore header files more
consistent with our header style.

src/include/access/sysattr.h

@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * sysattr.h
+ *	  POSTGRES system attribute definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $PostgreSQL: pgsql/src/include/access/sysattr.h,v 1.1 2008/05/12 00:00:53 alvherre Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SYSATTR_H
+#define SYSATTR_H
+
+
+/*
+ * Attribute numbers for the system-defined attributes
+ */
+#define SelfItemPointerAttributeNumber			(-1)
+#define ObjectIdAttributeNumber					(-2)
+#define MinTransactionIdAttributeNumber			(-3)
+#define MinCommandIdAttributeNumber				(-4)
+#define MaxTransactionIdAttributeNumber			(-5)
+#define MaxCommandIdAttributeNumber				(-6)
+#define TableOidAttributeNumber					(-7)
+#define FirstLowInvalidHeapAttributeNumber		(-8)
+
+
+#endif   /* SYSATTR_H */