zink: Enable PIPE_CAP_PACKED_UNIFORMS.

We already support everything necessary and just need to ask the frontend
to DTRT.  This makes UBO0 get more tightly packed, saving upload space,
and allows for _mesa_optimize_state_parameters() as well.

src/gallium/drivers/zink/zink_compiler.c

@@ -387,6 +387,7 @@ zink_screen_init_compiler(struct zink_screen *screen)
       .lower_vector_cmp = true,
       .lower_int64_options = 0,
       .lower_doubles_options = ~nir_lower_fp64_full_software,
+      .lower_uniforms_to_ubo = true,
       .has_fsub = true,
       .has_isub = true,
       .lower_mul_2x32_64 = true,
@@ -931,7 +932,6 @@ zink_shader_finalize(struct pipe_screen *pscreen, void *nirptr, bool optimize)
       tex_opts.lower_tg4_offsets = true;
       NIR_PASS_V(nir, nir_lower_tex, &tex_opts);
    }
-   NIR_PASS_V(nir, nir_lower_uniforms_to_ubo, 16);
    if (nir->info.stage == MESA_SHADER_GEOMETRY)
       NIR_PASS_V(nir, nir_lower_gs_intrinsics, nir_lower_gs_intrinsics_per_stream);
    optimize_nir(nir);

src/gallium/drivers/zink/zink_screen.c

@@ -267,6 +267,7 @@ zink_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_CLEAR_SCISSORED:
    case PIPE_CAP_INVALIDATE_BUFFER:
    case PIPE_CAP_PREFER_REAL_BUFFER_IN_CONSTBUF0:
+   case PIPE_CAP_PACKED_UNIFORMS:
       return 1;
 
    case PIPE_CAP_TEXTURE_MIRROR_CLAMP_TO_EDGE: