SwiftShader can now be tested directly with dEQP, without using the
system's Vulkan loader or layers.

Bug b/116336664

Change-Id: I08816b5fb893d048c3dfe325ff54f44c646b250f
Reviewed-on: https://swiftshader-review.googlesource.com/c/22868Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>