isc-dhcp: don't crash if the network is restarted

Previously if the network interfaces (bridges and vlans especially)
went away and dhcpd was listening on them, it would die ignominiously.
Add support for restarting the service is the interfaces it was
listening on get kicked out from under it.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>

Author: pprindeville

net/isc-dhcp/Makefile

@@ -11,7 +11,7 @@ PKG_NAME:=isc-dhcp
 UPSTREAM_NAME:=dhcp
 PKG_REALVERSION:=4.4.3-P1
 PKG_VERSION:=4.4.3_p1
-PKG_RELEASE:=13
+PKG_RELEASE:=14
 
 PKG_LICENSE:=BSD-3-Clause
 PKG_LICENSE_FILES:=LICENSE

net/isc-dhcp/files/dhcpd.init

@@ -702,6 +702,7 @@ EOF
 
 	procd_open_instance
 	procd_set_param command $PROG -q -f -cf $config_file -lf $lease_file $dhcp_ifs
+	procd_set_param netdev $dhcp_ifs
 	procd_close_instance
 }