If compiling RESCUE always ignore feature_present(3) calls so that

a /rescue/ifconfig more modern than the kernel could still configure
IPv4 or IPv6 addresses.

Reported by:	Andrzej Tobola (ato iem.pw.edu.pl)
Reported by:	gcooper
MFC after:	1 day
X-MFC:		will not MFC any time soon, just reminder for r222527

sbin/ifconfig/af_inet.c

@@ -200,7 +200,10 @@ static struct afswtch af_inet = {
 static __constructor void
 inet_ctor(void)
 {
+
+#ifndef RESCUE
 	if (!feature_present("inet"))
 		return;
+#endif
 	af_register(&af_inet);
 }

sbin/ifconfig/af_inet6.c

@@ -545,8 +545,10 @@ inet6_ctor(void)
 #define	N(a)	(sizeof(a) / sizeof(a[0]))
 	size_t i;
 
+#ifndef RESCUE
 	if (!feature_present("inet6"))
 		return;
+#endif
 
 	for (i = 0; i < N(inet6_cmds);  i++)
 		cmd_register(&inet6_cmds[i]);

sbin/ifconfig/ifconfig.c

@@ -498,9 +498,11 @@ ifconfig(int argc, char *const *argv, int iscreate, const struct afswtch *uafp)
 	 * ifconfig IF up/down etc. to work without INET support as people
 	 * never used ifconfig IF link up/down, etc. either.
 	 */
+#ifndef RESCUE
 #ifdef INET
 	if (afp == NULL && feature_present("inet"))
 		afp = af_getbyname("inet");
+#endif
 #endif
 	if (afp == NULL)
 		afp = af_getbyname("link");