import gprs_gsup_message.[ch] from openbsc as gsup.[ch]

Move those routines from OpenBSC to libosmogsm, so they can be
re-used from other programs.  I think it was a mistake to add them only
inside the openbsc repository in the first place.  We need to pay more
attention to this in the future.
diff --git a/include/osmocom/core/logging.h b/include/osmocom/core/logging.h
index 4b79c05..89d3f94 100644
--- a/include/osmocom/core/logging.h
+++ b/include/osmocom/core/logging.h
@@ -91,7 +91,8 @@
 #define DLCTRL		-8	/*!< Control Interface */
 #define DLGTP		-9	/*!< GTP (GPRS Tunneling Protocol */
 #define DLSTATS		-10	/*!< Statistics */
-#define OSMO_NUM_DLIB	10	/*!< Number of logging sub-systems in libraries */
+#define DLGSUP		11	/*!< Generic Subscriber Update Protocol */
+#define OSMO_NUM_DLIB	11	/*!< Number of logging sub-systems in libraries */
 
 /*! Configuration of singgle log category / sub-system */
 struct log_category {