LUCENE-6299: fix deleteAll to deduct from pendingNumDocs more carefully; fix addIndexes to do best-effort check up front and only reserve for real just before changing SIS

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene6299@1662544 13f79535-47bb-0310-9956-ffa450edef68
4 files changed