i965: Add a brw_wm_prog_data::has_render_target_reads field.

State upload code should use prog_data rather than poking at shader_info
directly.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>

src/intel/compiler/brw_compiler.h

@@ -614,6 +614,7 @@ struct brw_wm_prog_data {
    bool uses_src_depth;
    bool uses_src_w;
    bool uses_sample_mask;
+   bool has_render_target_reads;
    bool has_side_effects;
    bool pulls_bary;