add osmo-mslookup-client program (#2)

Standalone program using libosmo-mslookup to easily integrate with programs
that want to connect services (SIP, SMS,...) to the current location of a
subscriber. Also useful for manual testing.

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).

Resubmit of 637bbfcd9275f8c47212b29b50110f56ba6397bf after revert in
41fe3625915c456513544b99ba8c057c0f650b3c.

Change-Id: Ie39d30e20461ab10ae3584863d8bfc6b76a12f37
diff --git a/.gitignore b/.gitignore
index eec364a..0965935 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,7 @@
 src/osmo-hlr-db-tool
 src/osmo-euse-demo
 src/gsupclient/gsup-test-client
+src/mslookup/osmo-mslookup-client
 
 tests/atconfig
 tests/testsuite