select: fixup timers

This commit adapts a timer model similar to what is used in IOCP

Previously, select would not order timers which would break some
other assumptions made in the code about timer ordering. This ensures
timeouts are ordered within the list.

Change-Id: Ia5fcc3237990806c18c5fb359c2b5a1af1ce78fc
Reviewed-on: http://review.couchbase.org/33108
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>