SGSN: print additional GTP-related info

* print libgtp version on startup
* print GSN addresses in 'sh sgsn'

Change-Id: I699a9eb56c4b362984ea8292a3d2b22b71f53c15
Related: SYS#3610
diff --git a/src/gprs/sgsn_main.c b/src/gprs/sgsn_main.c
index d79beb3..7036bf6 100644
--- a/src/gprs/sgsn_main.c
+++ b/src/gprs/sgsn_main.c
@@ -447,7 +447,8 @@
 	if (rc) {
 		LOGP(DGPRS, LOGL_FATAL, "Cannot bind/listen on GTP socket\n");
 		exit(2);
-	}
+	} else
+		LOGP(DGPRS, LOGL_NOTICE, "libGTP v%s initialized\n", gtp_version());
 
 	rc = gprs_subscr_init(&sgsn_inst);
 	if (rc < 0) {