Make "ant validate" also check svn working copy (we removed this check, because we wanted to be compatible with GIT checkouts or newer subversion repos). But we ignore those checks automatically, if its not a supported subversion.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624095 13f79535-47bb-0310-9956-ffa450edef68
Revert 1624095: The check is already done by precommit, I missed this!

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624101 13f79535-47bb-0310-9956-ffa450edef68