Fix issue where duplicate trace message was seen on sys targets

When prefixing a trace with a log level e.g.

    trace("warn", "message");

the output on sys target would be

    message,message

This was because we're using the original haxe trace function which will also print the `customParams` from the pos infos. Because we process these params in mconsle we don't want to keep them in the PosInfos object.