fake_camera: avoid deprecation warnings on g_mutex API.
fake_camera: avoid deprecation warnings on g_mutex API.

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