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/configure.ac b/openbsc/configure.ac
index 5c077ee..081e416 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -18,6 +18,9 @@
 dnl checks for libraries
 AC_SEARCH_LIBS(crypt, crypt,
     [LIBCRYPT="-lcrypt"; AC_DEFINE([VTY_CRYPT_PW], [], [Use crypt functionality of vty.])])
+AC_SEARCH_LIBS([dlopen], [dl dld], [LIBRARY_DL="$LIBS";LIBS=""])
+AC_SUBST(LIBRARY_DL)
+
 
 PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 0.6.4)
 PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 0.3.0)
@@ -162,6 +165,7 @@
     tests/bsc-nat-trie/Makefile
     tests/mgcp/Makefile
     tests/gprs/Makefile
+    tests/gbproxy/Makefile
     tests/si/Makefile
     tests/abis/Makefile
     tests/smpp/Makefile