lapdm: Create a simple test case to transmit data between both ends

This is testing the establishment of two ends (BTS, MS) one is in
the polling mode as used by osmo-bts. Transfer data between the two
ends. The sent data is not verified though. This should be followed
up soon.
diff --git a/configure.ac b/configure.ac
index 6348a79..c38d82f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -167,6 +167,7 @@
 	tests/a5/Makefile
 	tests/auth/Makefile
 	tests/conv/Makefile
+	tests/lapd/Makefile
 	utils/Makefile
 	Doxyfile.core
 	Doxyfile.gsm