* For the most part we implement this as a thin pass-through layer. Where we
care about things (image barriers for layout transitions and queue
submissions) we do two different things:
- For image barriers, we "downcast" to plain VkImageMemoryBarrier. Currently
the only thing that's unique to VkImageMemoryBarrier2KHR is extra access
flags and pipeline stages, which we don't care about. This keeps a lot of
code from having to either handle two paths or handle the new path and then
do lots of conversions back to VkImageMemoryBarrier when running on older
drivers.
- For queue submissions we do the opposite. We promote old VkSubmitInfo to
VkSubmitInfo2KHR and process that in a common function, then if necessary
we decay back to VkSubmitInfo before sending to the driver.
baldurk