Fix SPIRV-Tools deps in core validation layer. The spirv_tools_external_revision_generate action should no longer depend on ANGLE's DEPS file exclusively. We're using the version of SPIRV-Tools provided by Chromium or ANGLE depending on the client. Depending on DEPS directly should give the correct behaviour. Bug: chromium:926354 Change-Id: I87ac59f1e3f0d3a0b13df51fb6477940ff534dc7 Reviewed-on: https://chromium-review.googlesource.com/c/1446495 Reviewed-by: Nico Weber <thakis@chromium.org>