LUCENE-5902: Handle different location for backcompat tests in trunk vs branch_4x (merged 1622604 from trunk)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1622605 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5902: Fix bug in previous commit

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1622607 13f79535-47bb-0310-9956-ffa450edef68
Add backcompat indexes for 4.10 format

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1622608 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5902: Make loadresource quiet (merged 1622572)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1622611 13f79535-47bb-0310-9956-ffa450edef68