Minor IOCP formatting/style fixups

This fixes a lot of the formatting, style, and dead code in the IOCP
plugin and brings it more up to date with the rest of the code.

Change-Id: I40840020dccd211594b9111a09d6555d7d373155
Reviewed-on: http://review.couchbase.org/40315
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>