silence clang unused function warnings and get rid of some unused functions

libs/sofia-sip/libsofia-sip-ua/iptsec/auth_module.c

@@ -80,10 +80,19 @@ char const auth_internal_server_error[] = "Internal server error";
 static void auth_call_scheme_destructor(void *);
 static void auth_md5_hmac_key(auth_mod_t *am);
 
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+#endif
+
 HTABLE_PROTOS_WITH(auth_htable, aht, auth_passwd_t, usize_t, unsigned);
 HTABLE_BODIES_WITH(auth_htable, aht, auth_passwd_t, APW_HASH,
 		   usize_t, unsigned);
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
 /**Allocate an authentication module instance.
  *
  * The function auth_mod_alloc() allocates an authentication module object.