Do not try to compile with plugins for Windows platform

Change-Id: Ibf6f7f598b1a646e222f325fdb42e4b500daa121
Reviewed-on: http://review.couchbase.org/27640
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>