Work around reported problem that AIX's getaddrinfo() doesn't seem to zero

sin_port in the returned IP address struct when servname is NULL.  This has
been observed to cause failure to bind the stats collection socket, and
could perhaps cause other issues too.  Per reports from Brad Nicholson
and Chris Browne.

src/backend/libpq/ip.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/libpq/ip.c,v 1.36 2006/06/20 19:56:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/libpq/ip.c,v 1.37 2006/10/19 17:26:32 tgl Exp $
  *
  * This file and the IPV6 implementation were initially provided by
  * Nigel Kukard <nkukard@lbsd.net>, Linux Based Systems Design
@@ -72,6 +72,15 @@ pg_getaddrinfo_all(const char *hostname, const char *servname,
 		return getaddrinfo_unix(servname, hintp, result);
 #endif
 
+#ifdef _AIX
+	/*
+	 * It seems AIX's getaddrinfo doesn't reliably zero sin_port when servname
+	 * is NULL, so force the issue.
+	 */
+	if (servname == NULL)
+		servname = "0";
+#endif
+
 	/* NULL has special meaning to getaddrinfo(). */
 	return getaddrinfo((!hostname || hostname[0] == '\0') ? NULL : hostname,
 					   servname, hintp, result);