Ignore win32 build artifacts

Change-Id: Ic698e4e6af6cfb6f8bfa345a9f98cec35e759dc1
Reviewed-on: http://review.couchbase.org/31629
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>