loader: gllavl#46 add check for device extensions
loader: gllavl#46 add check for device extensions

Make GetInstanceProcAddr check layers for device extensions.

Change-Id: Ib23c5d42d11be415e9a6acd3b8427d0e474087a5

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools