This commit adds an option to xt_quota2 called "no-change". The
effect of this option, when used, is that it will skip incrementing
or decrementing the quota counter, effectively providing a quota test
only.
The reason for implementing this is so that I could have a rule check
if quota is available for a rule in the PREROUTING tables, without
actually decrementing the amount of available quota. I only wanted to
decrement the amount of available quota in the FORWARD rule.
Otherwise, the first packet of every connection would be counted
twice.
