i965: Add handling for fp16 configs

Expose configs when allow_fp16_configs has been enabled and
DRI_LOADER_CAP_FP16 is set in the loader.

Also, define a new dri configuration option so users can disable exposure of
fp16 formats. Make fp16 opt-in for i965.

Signed-off-by: Kevin Strasser <kevin.strasser@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

src/util/xmlpool/t_options.h

@@ -274,6 +274,11 @@ DRI_CONF_OPT_BEGIN_B(allow_rgb565_configs, def) \
 DRI_CONF_DESC(en,gettext("Allow exposure of visuals and fbconfigs with rgb565 formats")) \
 DRI_CONF_OPT_END
 
+#define DRI_CONF_ALLOW_FP16_CONFIGS(def) \
+DRI_CONF_OPT_BEGIN_B(allow_fp16_configs, def) \
+DRI_CONF_DESC(en,gettext("Allow exposure of visuals and fbconfigs with fp16 formats")) \
+DRI_CONF_OPT_END
+
 /**
  * \brief Initialization configuration options
  */