Fix compile error with -Werror

Change-Id: Ifac2f0b1c06534bc85bad5fe2b2594c4eb208dda
Reviewed-on: http://review.couchbase.org/27387
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>