add Kc128 to gsm0808 Create Ciphering Command

Prepare for A5/4 support in osmo-msc.

Add new function gsm0808_create_cipher2() which takes a struct as
argument instead of individual fields. This is akin to e.g.
gsm0808_create_handover_request() below in the file, and allows
backwards compatibly extending the argument list without needing a new
function signature every time.

Add struct gsm0808_cipher_mode_command, as argument list for
gsm0808_create_cipher2(), with kc128 included.

Encode the Kc128 IE in gsm0808_create_cipher2().

Implement gsm0808_create_cipher() by calling gsm0808_create_cipher2().

Change-Id: Ib3906085e0c6e5a496a9f755f0f786238a86ca34
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 437599b..475ec02 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -170,6 +170,7 @@
 gsm0808_create_assignment_failure;
 gsm0808_create_ass_fail;
 gsm0808_create_cipher;
+gsm0808_create_cipher2;
 gsm0808_create_cipher_complete;
 gsm0808_create_cipher_reject;
 gsm0808_create_cipher_reject_ext;
@@ -218,6 +219,8 @@
 gsm0808_dec_channel_type;
 gsm0808_enc_encrypt_info;
 gsm0808_dec_encrypt_info;
+gsm0808_enc_kc128;
+gsm0808_dec_kc128;
 gsm0808_enc_cell_id_list;
 gsm0808_enc_cell_id_list2;
 gsm0808_dec_cell_id_list;