[CRIU] [PATCH 2/2]v2 service: add support for check request

[Pavel Emelyanov]

>>>>>>>>> +
>>>>>>>>> +	resp.kernel = true;
>>>>>>>> Always true argument is pointless.
>>>>>>> But resp.kernel = false after init. If cr_check() does not fail, we set
>>>>>>> resp.kernel to true, and if cr_check() does fail - resp.kernel = false.
>>>>>> So we have two types of responses:
>>>>>>
>>>>>> * kernel = true,  success = true  for OK
>>>>>> * kernel = false, success = false for not-OK
>>>>>>
>>>>>> Why is just success = <success-or-not> not enough?
>>>>> Here is what we've got:
>>>>>
>>>>> -- resp.success == false  -- options are wrong or something bad happened
>>>>> and check wasn't done
>>>>>
>>>>> -- resp.success == true and resp.check.kernel == true -- check was done
>>>>> and kernel features are ok
>>>>>
>>>>> -- resp.success == true and resp.check.kernel == false -- check was done
>>>>> and kernel features are not ok
>>>> I don't see this in the code -- resp.success = true and resp.kernel = true
>>>> are set together in one place.
> 
> Yes, it can't be such for now. But it is a preparation for further work. 
> Or you are not sure about adding more functionality to this request? We 
> may add check_dump/check_restore/check_images? as a separate ones. What 
> do you think?

If we want to extend req/resp later, we can do it with optional pb fields.
Plz, make only necessary amount of coding.