Option -k broken

[Frank Ch. Eigler]

Torsten Polle <Torsten.Polle@gmx.de> writes:

> stap --vp 0402 -k -e 'probe begin { off_task   = &@cast(0, "task_struct", "kernel<linux/sched.h>")->tasks; }' -p4
> [...]

Thanks for the recipe; that helped reproduce the problem, and fix the
main part of it.  (There is still another problem here related to 
verbose tracing & unresolveable @cast ops, but it's not as serious.)

- FChE