This structure will be internal to compel. Users will only see
one as opaque pointer and read data from it using calls.

Exception for now -- infect_ictx. This is a configuration structure
that will be embeded into ctl and seen outside.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>