CCBC-429: Select: fix timer scheduling

Fixes a rather serious bug in which select would busy loop if there was
a timer ahead of schedule. I do not understand how this was not noticed
before.

Change-Id: I8cd093eb000dcf21b7a5f34860958ee9ce00d628
Reviewed-on: http://review.couchbase.org/37564
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>