In the fast-link case, we should just use the library shader and assume
that it's correct. We have to do this because we may not have a
precompiled shader in this case so we can't even generate the shader
hash.
In the link optimization case, we could still have a library shader
coming in from some library pipeline. That shader may happen to be
correct, in which case we can just use it and not even bother digging
around in the cache. In the more likely case, the keys won't match and
we should throw it away before we look up a different shader in the
cache and leak our reference.
Fixes: 9308e8d90d ("vulkan: Add generic graphics and compute VkPipeline implementation")
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27860>
bb8b11d806