This had previously been masked by other failures, so we didn't notice.
Bitcasting Int to Float4 is incorrect.

Test: dEQP-VK.subgroups.*
Change-Id: Ib66fb3a458d44c6689977006454bbc7719a1373f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30089Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>