include these changes from ep-engine:
d2a6b7534f5939115de092094186c55fca268a0b  Sundar Sridharan   [BP] MB-9692 Handle MutationLog lseek errors gracefully
c3e3e74a898263897c4b78965b6785ac907c04ce  Chiyoung Seo       MB-9800 Always respond to CHECKPOINT_PERSISTENCE through flusher

Change-Id: I454af2383b8d414a4850f61af61899240d016f55
Reviewed-on: http://review.couchbase.org/32776
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>