toy-indexing.xml: Update memcached and ep-engine revision

Change-Id: I3c1b91d66013246a41d332530d6f01bfce35d9ad
Reviewed-on: http://review.couchbase.org/42341
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>