Fix make install target for windows

Change-Id: If30ccd8a47e7887e84c7398ec8b1fe4d2ff857c9
Reviewed-on: http://review.couchbase.org/24314
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>