allow for write.lock (NativeFSLF leaves this) too

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1625805 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5957: Add option for tests to not randomize codec (merged 1625812)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1625814 13f79535-47bb-0310-9956-ffa450edef68