traceBatch Verbosity problem

[Stephen Weeks]

> Another possibility would be to move the tracers inside the functions, so that
> there is a verbosity test once per compile (or chunk, or something better than
> per function call).  Although you should probably measure the time to see if it
> matters.

Forget what I said.  This is noise.  It just pushes the test on the bool ref
into a switch on the datatype variant representing the lambda.  I guess the
latter is slightly better since there's no deref, but there's still a test.

I'd say go for the test, since that's gotta be cheaper than counting the time.