Fix up some compiler warnings in cbc

Change-Id: I266a3692140c9b85bcdeaf8d98e458a72b9931c1
Reviewed-on: http://review.couchbase.org/42771
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>