First time regs are saved on ctl->orig.regs in parasite_prep_ctl,
the 2nd time regs are got inside x86/arch_task_compatible, while
it can use the on-ctl copy.

travis-ci: success for Don't get task regs twice
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>