Auth: Import milenage implementation from hostap (Jouni Malinen)

... and add integration into the osmo_auth core.
diff --git a/src/gsm/auth_core.c b/src/gsm/auth_core.c
index 78121bf..c578df9 100644
--- a/src/gsm/auth_core.c
+++ b/src/gsm/auth_core.c
@@ -71,7 +71,7 @@
 		      struct osmo_sub_auth_data *aud,
 		      const uint8_t *_rand)
 {
-	struct osmo_auth_impl *impl = selected_auths[aud->type];
+	struct osmo_auth_impl *impl = selected_auths[aud->algo];
 
 	if (!impl)
 		return -ENOENT;
@@ -84,7 +84,7 @@
 			   const uint8_t *rand_auts, const uint8_t *auts,
 			   const uint8_t *_rand)
 {
-	struct osmo_auth_impl *impl = selected_auths[aud->type];
+	struct osmo_auth_impl *impl = selected_auths[aud->algo];
 
 	if (!impl || !impl->gen_vec_auts)
 		return -ENOENT;