argued against "if" logic as part of the defined part of Ant stating
that all logic really should go into tasks. Now that the object model
is clean enough, it becomes silly obvious how to do this without requiring
the addition of any if/unless attributes in the target definitions themselves.

The build target task takes a target name and, optionally a if property. If
the property is used and is "true", then the target is executed by calling
the appropriate functionality on the Project object.


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@268340 13f79535-47bb-0310-9956-ffa450edef68