isc-dhcp: write resolv.conf per network & dhcp settings

The internal nameservers and the DHCP default domain should be
squirted into /tmp/resolv.conf.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
(cherry picked from commit db6adb616d)

net/isc-dhcp/files/dhcpd.init

@@ -263,6 +263,11 @@ general_config() {
 	echo "max-lease-time $max_lease_time;"
 
 	[ -n "$domain" ] && echo "option domain-name \"$domain\";"
+
+	rm -f /tmp/resolv.conf
+	echo "# This file is generated by the DHCPD service" > /tmp/resolv.conf
+	[ -n "$domain" ] && echo "domain $domain" >> /tmp/resolv.conf
+	echo "nameserver 127.0.0.1" >> /tmp/resolv.conf
 }
 
 start_service() {