LUCENE-5980: don't let document length overflow

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1629835 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5993: Remove DocIdBitSet, WAH8DocIdSet and PForDeltaDocIdSet.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1629838 13f79535-47bb-0310-9956-ffa450edef68