GUACAMOLE-221: Merge handle FREERDP_ERROR_* constants only when defined.
GUACAMOLE-221: Merge handle FREERDP_ERROR_* constants only when defined.


mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,apache/guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,apache/guacamole-server,glyptodon/guacamole-server,apache/guacamole-server