removed compilation warning

PR:	bin/71624

usr.sbin/rtadvd/config.c

@@ -53,6 +53,7 @@
 #include <syslog.h>
 #include <errno.h>
 #include <string.h>
+#include <search.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <ifaddrs.h>

usr.sbin/rtadvd/timer.c

@@ -36,6 +36,7 @@
 #include <syslog.h>
 #include <stdlib.h>
 #include <string.h>
+#include <search.h>
 #include "timer.h"
 
 static struct rtadvd_timer timer_head;