Actually print what is unhandled so we can fix it.

Change-Id: I98ef49cf2f3f3882a8c4296578af4880c2542240
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/29270
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>