Handle present request for multiple swapchains
requested to merge iason.paraskevopoulos/vulkan-wsi-layer:multiple_swapchains_present_req into master
Adds an additional semaphore for every swapchain image to be waited for before the present engine access an image. During a present request with multiple swapchains, these semaphores are grouped together and are signaled after the incoming pWaitSemaphores signal.
Signed-off-by: Iason Paraskevopoulos iason.paraskevopoulos@arm.com Change-Id: I94cabbf5f7d9a45dceef60eec7773b48ccc32078