message: Fix enc lib v4 rpc error.
diff: @@ -898,7 +898,7 @@ int SeafileRpcClient::generateMagicAndRandomKey(int enc_version,
  char *c_magic = NULL;
  char *c_random_key = NULL;
  char *c_salt = NULL;
  - if (enc_version == 3) {
  + if (enc_version == 3 || enc_version == 4) {
  g_object_get (obj,
  "magic", &c_magic,
  "random_key", &c_random_key,
  