SwiftConfig is unused in Vulkan, so it was removed.

Change-Id: Ic82bd186c271522b8552ca9925692e311b5c4156
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32031Tested-by: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>