add gsm0341_test to generate SMSCB hex strings

Those hex strings can then be copy+pasted into the OSmoNITB VTY
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index d82c8a0..02c8884 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -38,6 +38,8 @@
 gprs_tlli_type;
 gprs_tmsi2tlli;
 
+gsm0341_build_msg;
+
 gsm0480_create_notifySS;
 gsm0480_create_unstructuredSS_Notify;
 gsm0480_create_ussd_resp;