CCBC-207: Check exceptfds in select

Change-Id: Ie4ea98fe76b57b7c0a620c6a638771f334221cdc
Reviewed-on: http://review.couchbase.org/27984
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>