Return vkDestroyDevice from vkGetDeviceProcAddr
The vkDestroyDevice entrypoint was listed as a instance level entrypoint, that is, to be returned by vkGetInstanceProcAddr; however, vkDestroyDevice is a device level entrypoint. Consequently, the layer implementation was not called by the loader upon application calls to vkDestroyDevice and this caused memory leaks within the layer.
Signed-off-by: David Harvey-Macaulay david.harvey-macaulay@arm.com