Merged revision(s) 1571109 from lucene/dev/trunk:
LUCENE-5467: Add "ant clean-jars" to make a complete renewal with IVY resolve possible.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1571110 13f79535-47bb-0310-9956-ffa450edef68