intel/fs: Copy color_outputs_valid into wm_prog_data

Fixes: 36ee2fd61c ("anv: Implement the basic form of VK_EXT_transform_feedback")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16506>

src/intel/compiler/brw_compiler.h

@@ -868,6 +868,7 @@ struct brw_wm_prog_data {
       /** @} */
    } binding_table;
 
+   uint8_t color_outputs_written;
    uint8_t computed_depth_mode;
    bool computed_stencil;
 

src/intel/compiler/brw_fs.cpp

@@ -9774,6 +9774,7 @@ brw_nir_populate_wm_prog_data(const nir_shader *shader,
                           key->emit_alpha_test;
    prog_data->uses_omask = !key->ignore_sample_mask_out &&
       (shader->info.outputs_written & BITFIELD64_BIT(FRAG_RESULT_SAMPLE_MASK));
+   prog_data->color_outputs_written = key->color_outputs_valid;
    prog_data->computed_depth_mode = computed_depth_mode(shader);
    prog_data->computed_stencil =
       shader->info.outputs_written & BITFIELD64_BIT(FRAG_RESULT_STENCIL);