gbproxy: Add test program to test gbproxy message handling

This program tests the gbproxy implementation by passing NS messages
to a modified gbproxy that dumps the resulting messages, signals, and
state.

It focusses on testing abnormal situations like port changes.

Ticket: OW#874
Sponsored-by: On-Waves ehf
diff --git a/openbsc/.gitignore b/openbsc/.gitignore
index 5955482..7525a4e 100644
--- a/openbsc/.gitignore
+++ b/openbsc/.gitignore
@@ -60,6 +60,7 @@
 tests/sms/sms_test
 tests/timer/timer_test
 tests/gprs/gprs_test
+tests/gbproxy/gbproxy_test
 tests/abis/abis_test
 tests/si/si_test
 tests/smpp/smpp_test