WSI/intel: Implement newer semantics in how pCount is to be used.
WSI/intel: Implement newer semantics in how pCount is to be used.

A relatively-recent change in the WSI spec says that the value pointed to by
the pCount parameter should be updated if the other pointer (to the data to
return) is NULL.  Otherwise, pCount is the number of items of data to return
(i.e. the application can ask for a different number than it should ask for).

KhronosGroup/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,elongbug/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,KhronosGroup/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,elongbug/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,sashinde/VulkanTools,critsec/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,critsec/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,elongbug/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,KhronosGroup/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,Radamanthe/VulkanSamples