vulkan: update Vulkan headers to 1.0.49

Key changes since 1.0.46:
* Add VK_KHR_get_surface_capabilities2
* Add VK_KHR_shared_presentable_image
* Add VkObjectType enumeration to core API

The extensions had already been added manually in our internal tree,
so this just moves the existing declarations to the same place as in
the public header and fixes one small difference.

Test: dEQP-VK.wsi.android.surface.query_capabilities2
      dEQP-VK.wsi.android.shared_presentable_image.*
Change-Id: I1e4bd5d19f36af0d4e878b3971145a1ae1281dd6