Lift restriction on json-c <= 0.12.1
ipc-server: Acquire ownership of referenced json_object properly
When adding a referenced json_object with an unknown lifetime to
another json_object, it must be done with a wrapped call to
json_object_get() to acquire the ownership of that json_object.
to 0.12.1. This is needed because the development
version breaks the existing API of json_object_array_length()
by moving the return from int to size_t.
This would fix#1355
