Remove warnings and notices.

First, some versions of memcached and the memcache extension need an extra parameter on delete() to prevent a noticed like this from appearing:
CLIENT_ERROR bad command line format. Usage: delete [noreply]

Adding the "optional" zero timeout parameter makes it work without error. More info at:
http://stackoverflow.com/questions/4745345/how-do-i-stop-phpmemcachedele...

Second, in similar situations, requesting the "malloc" stats will not only return an empty result, but throw a notice as well.