MB-7250:  make changes suggested by Xcode

Change-Id: I8d4d0cea68a7b03e69520080d1685b48881a616d
Reviewed-on: http://review.couchbase.org/41338
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>