Implement the mslookup server to service remote mslookup requests.
This patch merely adds the logic to answer incoming mslookup requests, an
actual method to receive requests (mDNS) follows in a subsequent patch.
- API to configure service names and addresses for the local site (per MSC).
- determine whether a subscriber is on a local MSC
(checking the local proxy will be added in subsequent patch that adds proxy
- VTY config follows in a subsequent patch.
For a detailed overview of the D-GSM and mslookup related files, please see the
elaborate comment at the top of mslookup.c (already added in an earlier patch).