3DSTATE_CONSTANT_* looks at prog_data->ubo_ranges. We were getting
saved by iris_set_constant_buffers() usually happening when changing
programs (as they usually change uniforms too), but with the clear
shader that doesn't use uniforms, we weren't getting one and were
leaving push constants enabled, screwing things up.
Also clean up a bit of a mess left by the hacks - we were missing
bindings in the VS/FS/CS case, among other issues...
84a419432d