add gsm0808_amr_modes_from_cfg

Provide the definitions from 3GPP TS 28.062, Table 7.11.3.1.3-2 as
generally usable API.

Likely users:
- upcoming patch to improve conversion between S0-S15 and MultiRate
  config, I900fda192742fa8f6dd54e9131ef1704b14cc41a
- osmo-msc to figure out conversion between SDP AMR mode-set and 3GPP TS
  48.008 Permitted Speech S0-S15.
- osmo-bsc to choose AMR modes for channel activation from cfg /
  permitted speech from MSC.

Related: SYS#5066
Change-Id: Icef7dd626d3d4641c66b8dd87e2047fc0ab547d1
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 21f8e15..6ad363f 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -252,6 +252,8 @@
 gsm0808_speech_codec_from_chan_type;
 gsm0808_sc_cfg_from_gsm48_mr_cfg;
 gsm48_mr_cfg_from_gsm0808_sc_cfg;
+gsm0808_amr_modes_from_cfg;
+gsm0808_amr_mode_names;
 gsm0808_speech_codec_type_names;
 gsm0808_permitted_speech_names;
 gsm0808_chosen_enc_alg_names;