compositeAlpha on Wayland
wsi_common_wayland.c creats prime buffer with alpha only when compositeAlpha is VK_COMPOSITE_ALPHA_PRE_MULTIPLIED_BIT_KHR. Shouldn't be VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR? Spec says, "VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR: The alpha channel, if it exists, of the images is respected in the compositing process. The non-alpha channels of the image are not expected to already be multiplied by the alpha channel by the application; instead, the compositor will multiply the non-alpha channels of the image by the alpha channel during compositing." Same issue with XWindows.