Change the syntax of ipfw named states

[ae]

Summary

I'm going to merge ipfw changes from head/ to stable/11 and thus I decided to change the syntax that we use for named states.
To avoid ambiguity I prefixed the state name with a colon.

[julian]

we are going to run out of available tricks for this in ipfw at some stage.. Can we re-use () like used in table? or make the : part of the keep-state.. so that "keep_state: state1" or keep_state(state1) vs "keep_state :state1"

[ae]

In D9929#205426, @julian wrote:

we are going to run out of available tricks for this in ipfw at some stage.. Can we re-use () like used in table? or make the : part of the keep-state.. so that "keep_state: state1" or keep_state(state1) vs "keep_state :state1"

In general we have no preference about the syntax. But inventing the similar syntax for "limit" rules seems not so obvious. Also I don't see how such trick can prevent to use it later for another opcode.

[ae]

Julian, if you have no objection I'll commit it tomorrow.

[ae]

Committed in r315305.