Fix T47158: Labels w/ icons use button text color

Icon buttons with text labels now use the same color as labels.

This was causing problems with theming since there was no way to set color
for all labels without also changing button text color.

source/blender/editors/interface/interface_widgets.c

@@ -3492,6 +3492,8 @@ static uiWidgetType *widget_type(uiWidgetTypeEnum type)
 			
 		/* specials */
 		case UI_WTYPE_ICON:
+			/* behave like regular labels (this is simply a label with an icon) */
+			wt.state = widget_state_label;
 			wt.custom = widget_icon_has_anim;
 			break;