MSVC does not support %zu

Change-Id: Iedc909a654137cd7b471dbc97edeaf6941d02ecb
Reviewed-on: http://review.couchbase.org/40652
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Merge remote-tracking branch 'membase/3.0'

* membase/3.0:
  MSVC does not support %zu

Change-Id: I6a0bf528ed56fc5ad5944130a1946344d41b2b92