The translator outputs intermediate shaders for Vulkan that are later to
be modified by the SPIR-V transformer.  glslang has no business trying
to link them.

Bug: angleproject:5740
Change-Id: I9ae418f54b91312b5fd0ef794acbc46a40261a0e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2753096
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Ian Elliott <ianelliott@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>