Merged revision(s) 1610929 from lucene/dev/trunk:
LUCENE-5681: Fix RAMDirectory's IndexInput to not do double buffering on slices (causes useless data copying, especially on random access slices).


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1610930 13f79535-47bb-0310-9956-ffa450edef68