Check to see if /usr/bin/logger exists before using it. Use "echo" if

/usr/bin/logger is not available.

Noticed from:	error messages in -CURRENT's sysinstall Alt-F2 debug screen

contrib/isc-dhcp/client/scripts/freebsd

@@ -1,6 +1,10 @@
 #!/bin/sh
 
-LOGGER="/usr/bin/logger -s -p user.notice -t dhclient"
+if [ -x /usr/bin/logger ]; then
+	LOGGER="/usr/bin/logger -s -p user.notice -t dhclient"
+else
+	LOGGER=echo
+fi
 
 make_resolv_conf() {
   echo search $new_domain_name >/etc/resolv.conf