post 2.6.5-rc0
SERVER-15319 Forward-compatible change for 2.8 freelist

Makes NamespaceDetails::orphanDeletedList() also orphan the new 2.8-only
deleted lists. This ensures that 2.8 won't attempt to reuse the space in
extents that no longer belong to this collection.
BUMP 2.6.5-rc1
Merge remote-tracking branch 'upstream/v2.6' into v2.6