Fixes several possible crash issues that might occur on Intel-based Macs
and older macOS versions:
On modern macOS versions (13+) allocated memory is zero-allocated by
default which makes NULL pointer checks work correctly after allocation.
On older macOS versions this is not the case, so the OBSAVCaptureInfo
struct needs to be zero-allocated to ensure the guards in the tick and
render functions bail out correctly.
On Intel-based Macs and/or older macOS versions passing a reference to
the OBSAVCapture instance inside the OBSAVCapture struct can lead to a
crash because of a possible circular reference that cannot be resolved
at runtime.
Passing only a reference of the OBSAVCapture to libobs and incrementing
the retain count at source creation (decrementing in when the source is
destroyed) avoids this issue entirely.
Some devices do not support all color formats at all resolutions, but
the capture card source automatically uses an available color format
and compares it against the available format for a specific resolution.
Without being able to change this format, some resolutions do not
work as CMIO will not be able to find a compatible format. Thus the
color format needs to be manually selected for capture card sources
as well.
