pillowfight: Don't use usleep on Win32

Change-Id: Ia8693752b08ede8ea0b13f85fdc7a955b4ecc083
Reviewed-on: http://review.couchbase.org/31641
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>