Don't make libev timers repeatable

lcb timers are "one-shot" timers. Ensure the timer is not set to
"repeat" itself.

Change-Id: I926fbb91d3c98a41483a4eacf9bc10d634a4a2e3
Reviewed-on: http://review.couchbase.org/27985
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>