finish openbsc / libosmocore separation

* use pkg-config from openbsc to find header and library
* move sms and timer tests to libosmocore itself
* ensure "make distcheck" works on both packages
diff --git a/openbsc/tests/sccp/sccp_test.c b/openbsc/tests/sccp/sccp_test.c
index 562e134..982c168 100644
--- a/openbsc/tests/sccp/sccp_test.c
+++ b/openbsc/tests/sccp/sccp_test.c
@@ -28,7 +28,7 @@
 
 #include <openbsc/gsm_data.h>
 #include <openbsc/debug.h>
-#include <openbsc/msgb.h>
+#include <osmocore/msgb.h>
 
 #include <sccp/sccp.h>