ep.dll should go in lib/memcached

Change-Id: I00c4a076a6420a69f73cffb8a9c9d8811237af1b
Reviewed-on: http://review.couchbase.org/35517
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>