Conditionalize all code that uses tcpd.h behind LIBWRAP guard

This will allow the code to stand by itself without libwrap

MFC after:	2 weeks

libexec/tftpd/Makefile

@@ -1,12 +1,17 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/4/93
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 PROG=	tftpd
 MAN=	tftpd.8
 SRCS=	tftp-file.c tftp-io.c tftp-options.c tftp-transfer.c tftp-utils.c
 SRCS+=	tftpd.c
 WFORMAT=0
 
+.if ${MK_TCP_WRAPPERS} != "no"
+CFLAGS+=	-DLIBWRAP
 LIBADD=	wrap
+.endif
 
 .include <bsd.prog.mk>

libexec/tftpd/tftpd.c

@@ -66,7 +66,6 @@ __FBSDID("$FreeBSD$");
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
-#include <tcpd.h>
 #include <unistd.h>
 
 #include "tftp-file.h"
@@ -75,6 +74,10 @@ __FBSDID("$FreeBSD$");
 #include "tftp-transfer.h"
 #include "tftp-options.h"
 
+#ifdef	LIBWRAP
+#include <tcpd.h>
+#endif
+
 static void	tftp_wrq(int peer, char *, ssize_t);
 static void	tftp_rrq(int peer, char *, ssize_t);
 
@@ -281,6 +284,7 @@ main(int argc, char *argv[])
 		}
 	}
 
+#ifdef	LIBWRAP
 	/*
 	 * See if the client is allowed to talk to me.
 	 * (This needs to be done before the chroot())
@@ -329,6 +333,7 @@ main(int argc, char *argv[])
 				    "Full access allowed"
 				    "in /etc/hosts.allow");
 	}
+#endif
 
 	/*
 	 * Since we exit here, we should do that only after the above