Fix some edge cases in xinetd file descriptor handling

This change fixes the case where the listening file descriptor is in 0~2
range (easily reprodutible with a single UDP service)

PR:		211038
Obtained from:	pfSense
MFH:		2016Q3
Sponsored by:	Rubicon Communications (Netgate)

security/xinetd/Makefile

@@ -3,7 +3,7 @@
 
 PORTNAME=	xinetd
 PORTVERSION=	2.3.15
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	security ipv6
 MASTER_SITES=	GENTOO
 

security/xinetd/files/patch-xinetd_child.c

@@ -0,0 +1,24 @@
+--- xinetd/child.c.orig	2016-07-13 19:00:31 UTC
++++ xinetd/child.c
+@@ -168,7 +168,8 @@ void exec_server( const struct server *s
+    }
+ #endif
+ 
+-   (void) Sclose( descriptor ) ;
++   if ( descriptor > MAX_PASS_FD )
++      (void) Sclose( descriptor ) ;
+ 
+ #ifndef solaris
+ #if !defined(HAVE_SETSID)
+@@ -321,11 +322,6 @@ void child_process( struct server *serp 
+    signals_pending[0] = -1;
+    signals_pending[1] = -1;
+ 
+-   Sclose(0);
+-   Sclose(1);
+-   Sclose(2);
+-
+-
+ #ifdef DEBUG_SERVER
+    if ( debug.on )
+    {