gvfakecamera: mark constructor as new 0.8.0 API
gvfakecamera: mark constructor as new 0.8.0 API

Fake camera API was not meant as general public usage. We are now trying
to expose a sane API.

AravisProject/aravis,AravisProject/aravis,AravisProject/aravis,AravisProject/aravis,AravisProject/aravis