Newer Vulkan CTS has started providing this extension structure during
device creation.

Bug: b/139528538
Change-Id: Ie5c72dcc0b96b4d9e98a06a36fdecbdb25304e49
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35250Tested-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>