Extend GUC concepts of parse_hook and assign_hook to all four supported

datatypes, not only strings.  parse_hook is useless for bool, I suppose,
but it seems possibly useful for int and double to apply variable-specific
constraints that are more complex than simple range limits.  assign_hook
is definitely useful for all datatypes --- we need it right now for bool
to support date cache reset when changing Australian timezone rule setting.
Also, clean up some residual problems with the reset all/show all patch,
including memory leaks and mistaken reset of PostPortNumber.  It seems
best that RESET ALL not touch variables that don't have SUSET or
USERSET context.

src/backend/postmaster/postmaster.c

@@ -28,7 +28,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.218 2001/06/11 04:12:29 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.219 2001/06/12 22:54:05 tgl Exp $
  *
  * NOTES
  *
@@ -362,9 +362,13 @@ PostmasterMain(int argc, char *argv[])
 	/*
 	 * Options setup
 	 */
-	potential_DataDir = getenv("PGDATA");		/* default value */
+	ResetAllOptions(true);
 
-	ResetAllOptions();
+	/* PGPORT environment variable, if set, overrides GUC setting */
+	if (getenv("PGPORT"))
+		PostPortNumber = atoi(getenv("PGPORT"));
+
+	potential_DataDir = getenv("PGDATA");		/* default value */
 
 	/*
 	 * First we must scan for a -D argument to get the data dir. Then read