Fixes Burnout Paradies Remastered crashing on start when a camera is present.
The game creates qcap capture filter twice from devenum's moniker for some reason. Then, in actual graph, only one format is used. While v4l device can be opened multiple times it cannot really be used simultaneously. The second creation fails in set_caps() called from v4l_device_create(). Then, the game constructs just one dshow capture graph and with this patch camera actually works.
On Windows capture device also can't be really used simultaneously. But the filter creation would not ever fail, some failures and obscure behaviour only starts once the filter is connected into the graph and graph is started (i. e., actual frame capture takes place). If the device is opened in another process attempt to start a capture will fail. If it is already opened in the same process (like in included test), the behaviour is more convoluted: the second started graph will succeed and will be delivering samples while the first initialized graph will stop receiving samples. Then (at least here on Windows 11) attempt to change graph state on the first graph will result in MF error MF_E_VIDEO_RECORDING_DEVICE_PREEMPTED.
It is possible to implement that behaviour exactly of course by keeping a track of opened devices and closing those upon starting a new stream. But that will require quite some complications we tracking that, handling closed devices and synchronization. I suppose we don't need that until something depends on that (which is probably not all that likely). The present patch delays VIDIOC_S_FMT until stream initialization (using VIDIOC_TRY_FMT to test format caps during device creation) allowing multiple devices to be created and any first of them to be actually used, while attempt to init stream while another device is in use will fail.