Review uses of IsUnderPostmaster, change some tests to look at

whereToSendOutput instead because they are really inquiring about
the correct client communication protocol.  Update some comments.
This is pointing towards supporting regular FE/BE client protocol
in a standalone backend, per discussion a month or so back.

src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2003, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.56 2004/01/26 22:59:53 momjian Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.57 2004/01/28 21:02:40 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -1339,6 +1339,12 @@ pgstat_mainInit(void)
 {
 	IsUnderPostmaster = true;	/* we are a postmaster subprocess now */
 
+#ifdef EXEC_BACKEND
+	/* In EXEC case we will not have inherited these settings */
+	IsPostmasterEnvironment = true;
+	whereToSendOutput = None;
+#endif
+
 	MyProcPid = getpid();		/* reset MyProcPid */
 
 	/* Lose the postmaster's on-exit routines */