Move session_start out of MyProcPort stucture and make it a global called MyStartTime,

so that we will be able to create a cookie for all processes for CSVlogs.
It is set wherever MyProcPid is set. Take the opportunity to remove the now
unnecessary session-only restriction on the %s and %c escapes in log_line_prefix.

src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2007, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.161 2007/07/08 22:23:16 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.162 2007/08/02 23:39:44 adunstan Exp $
  * ----------
  */
 #include "postgres.h"
@@ -2168,6 +2168,8 @@ PgstatCollectorMain(int argc, char *argv[])
 
 	MyProcPid = getpid();		/* reset MyProcPid */
 
+	MyStartTime = time(NULL);  	/* record Start Time for logging */
+
 	/*
 	 * If possible, make this process a group leader, so that the postmaster
 	 * can signal any child processes too.  (pgstat probably never has