Since Vulkan doesn't support negative x or y viewport positions, this
patch concatenates a translation matrix to the projection matrix used in
Vulkan rendering. In this way, if a negative x or y coordinate would
be necessary, we can instead use a 0 coordinate and a
leftwards/upwards translation to achieve the same effect. This seems
to work alright with overlays, so as far as I can tell this patch
seems sufficient to get the behavior we want?
6701c0999b