Bug#547969: ivy jar not added to ant lib

[Onkar Shinde]

Ant upstream authors recommend using classpath attribute for optional
ant tasks when defining the task in build.xml.[1] Hence the symlink
should not be present in ant's library. Also the symlink modifies the
default classpath of ant which will cause problem if user wants to use
another version of ivy outside the system installation.

[1] http://ant.apache.org/manual/install.html#optionalTasks