colorstate: Drop xyz for now

Converting to and from xyz turns out to be more difficult than
expected, depending on what whitepoint you choose, And different
specs choose different whitepoints, so we can't directly map
css xyz to cicp xyz anyway.

gdk/gdkcicpparams.c

@@ -168,7 +168,6 @@ gdk_cicp_params_class_init (GdkCicpParamsClass *klass)
    * - 5: PAL
    * - 6,7: BT.601 / NTSC
    * - 9: BT.2020
-   * - 10: CIE XYZ
    * - 12: Display P3
    *
    * Since: 4.16

gdk/gdkcolorstate.c

@@ -676,10 +676,6 @@ gdk_color_state_new_for_cicp (const GdkCicp  *cicp,
       to_xyz = rec2020_to_xyz;
       from_xyz = xyz_to_rec2020;
       break;
-    case 10:
-      to_xyz = identity;
-      from_xyz = identity;
-      break;
     case 12:
       to_xyz = p3_to_xyz;
       from_xyz = xyz_to_p3;

tools/gtk-image-tool-utils.c

@@ -115,17 +115,6 @@ find_color_state_by_name (const char *name)
       gdk_cicp_params_set_matrix_coefficients (params, 0);
       gdk_cicp_params_set_range (params, GDK_CICP_RANGE_FULL);
 
-      color_state = gdk_cicp_params_build_color_state (params, &error);
-    }
-  else if (g_strcmp0 (name, "xyz") == 0)
-    {
-      params = gdk_cicp_params_new ();
-
-      gdk_cicp_params_set_color_primaries (params, 10);
-      gdk_cicp_params_set_transfer_function (params, 8);
-      gdk_cicp_params_set_matrix_coefficients (params, 0);
-      gdk_cicp_params_set_range (params, GDK_CICP_RANGE_FULL);
-
       color_state = gdk_cicp_params_build_color_state (params, &error);
     }
   else if (g_strcmp0 (name, "rec2020") == 0)
@@ -190,7 +179,7 @@ char **
 get_color_state_names (void)
 {
   static const char *names[] = {
-    "srgb", "srgb-linear", "display-p3", "xyz", "rec2020",
+    "srgb", "srgb-linear", "display-p3", "rec2020",
     "rec2100-pq", "rec2100-linear", "rec2100-hlg",
     "yuv", "bt601", "bt709",
     NULL,