gsm: Fix make distcheck with parallel make

Change-Id: I0bab4cfbc82d2b0aa7bd07769000ab8e4968a00b
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 1fd212d..dd28a15 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -733,6 +733,9 @@
 osmo_gad_dec_lon;
 osmo_gad_enc_unc;
 osmo_gad_dec_unc;
+osmo_gad_raw_read;
+osmo_gad_raw_write;
+osmo_gad_type_names;
 
 local: *;
 };