Fix AbstractAntLogger

The AbstractAntLogger class logs the message only if Ant Task is not null:

protected void antLog(Project proj, Task task, String aMsg, int antLogLevel) {
        if (task != null) {
            proj.log(task, aMsg, antLogLevel);
        }
    }

As a consequence, no log is availalbe in case when code it's called outside Ant - problem was found in open-source Gradle Clover Plugin.