Ignore build artifacts generated on win32

Change-Id: Iabe6b978e79d1b24ebd25be4546b90216f486a98
Reviewed-on: http://review.couchbase.org/30084
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>