The VA_DRIVER_INIT_FUNC macro is defined by configure in config.h, if
this header is not included then the init symbol will not be present and
libVA will not be able to load this backend.
This VA backend uses v4l2's Frame API proposal to interface with the
"sunxi-cedrus" video driver on Allwinner SoC. Only a few parts of the
code are really dependent on sunxi-cedrus and this VA backend could be
reused for other v4l drivers using the Frame API.
Maxime Ripard