[Bro] How to construct constant "time" values

[Vern Paxson]

> I am curious how it is possible to constuct some constant value x that
> make the following line valid:
> 
> have_request ? network_time() : x

It's not.  Currently, there are no constructors for absolute time values.
This is because a convincing need for them hasn't come up.  If you have
one, let's hear it!, and then we can considering adding this functinonality.

		Vern