TT#12300 Depend on net-tools in ngcp-services-* packages

ifconfig is required for our heartbeat-2 package:

| Starting High-Availability services:
| /usr/lib/ocf/resource.d//heartbeat/IPaddr: 312: /usr/lib/ocf/resource.d//heartbeat/IPaddr: ifconfig: not found

The net-tools package became "Priority: optional"
with stretch, so it's no longer installed by default.

Change-Id: I451445897f8af66ace4b1bf24a93de1323909b4b

debian/control

@@ -261,9 +261,10 @@ Depends:
  ldap-utils,
  linux-headers-amd64,
  linux-image-amd64,
- monit,
  mariadb-client,
  mariadb-server,
+ monit,
+ net-tools,
  ngcp-api-tools,
  ngcp-asterisk-voicemail-odbcstorage,
  ngcp-backup-tools,
@@ -333,6 +334,7 @@ Depends:
  kannel,
  mariadb-client,
  mariadb-server,
+ net-tools,
  ngcp-api-tools,
  ngcp-asterisk-voicemail-odbcstorage,
  ngcp-billing-tools,
@@ -399,9 +401,10 @@ Depends:
  ldap-utils,
  linux-headers-amd64,
  linux-image-amd64,
- monit,
  mariadb-client,
  mariadb-server,
+ monit,
+ net-tools,
  ngcp-api-tools,
  ngcp-asterisk-voicemail-odbcstorage,
  ngcp-backup-tools,