[sccp] Implement parts of ITU SCCP for use in the A-Interface

include/sccp/sccp_types.h contain Q.713 and GSM definitions
include/sccp/sccp.h is the application interface resembling
                    the esentials of the UNIX socket interface.

src/sccp.c is the actual implementation of SCCP featuring
           connection and UDT1 support.

tests/sccp/sccp.c is testing connection creation and formating
                  of the SCCP messages used by the A-interface. And
                  it contains a simple fuzzing test to test the
                  robustnes of the implementation.
diff --git a/openbsc/include/sccp/Makefile.am b/openbsc/include/sccp/Makefile.am
new file mode 100644
index 0000000..42fd310
--- /dev/null
+++ b/openbsc/include/sccp/Makefile.am
@@ -0,0 +1 @@
+noinst_HEADERS = sccp_types.h sccp.h