Also add SPIRV-Tools, as this was missing and caused red squiggles.

Bug: b/145351270
Change-Id: I22e664bb662f75284cf93cf6e446e775521c7b26
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38908Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>