gsm29118: add generator functions for GSM29118 messages

We already have some GSM29118 related definitions and functions in
libosmocore. Lets also add some functions to generate GSM29118 messages
(similar to those we have for GSM0808).

Change-Id: Ic87f8a771b87b52215d0a7451b67794557b80b8a
Related: OS#3615
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 04a9826..e9a9e4f 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -219,6 +219,21 @@
 gsm0808_lcls_control_names;
 gsm0808_lcls_status_names;
 
+gsm29118_msgb_alloc;
+gsm29118_create_alert_req;
+gsm29118_create_dl_ud;
+gsm29118_create_eps_det_ack;
+gsm29118_create_imsi_det_ack;
+gsm29118_create_lu_ack;
+gsm29118_create_lu_rej;
+gsm29118_create_mm_info_req;
+gsm29118_create_paging_req;
+gsm29118_create_reset_ack;
+gsm29118_create_reset_ind;
+gsm29118_create_status;
+gsm29118_create_release_req;
+gsm29118_create_service_abort_req;
+
 gsm0858_rsl_ul_meas_enc;
 
 gsm338_get_sms_alphabet;