libcompel: Drop cmdline members from argv_desc_t

We pass plugins arguments with separate option now.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
compel: pack -- Rename arguments

We already use a lot of "lib" prefix, so name
object files are they are -- @obj.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>