renderer: add field to indicate color transform support

include/wlr/render/wlr_renderer.h

@@ -40,6 +40,13 @@ struct wlr_renderer {
 		struct wl_signal lost;
 	} events;
 
+	struct {
+		/**
+		 * Does the renderer support color transforms on its output?
+		 */
+		bool output_color_transform;
+	} features;
+
 	// private state
 
 	const struct wlr_renderer_impl *impl;

render/gles2/renderer.c

@@ -526,6 +526,7 @@ struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_egl *egl) {
 		return NULL;
 	}
 	wlr_renderer_init(&renderer->wlr_renderer, &renderer_impl, WLR_BUFFER_CAP_DMABUF);
+	renderer->wlr_renderer.features.output_color_transform = false;
 
 	wl_list_init(&renderer->buffers);
 	wl_list_init(&renderer->textures);

render/pixman/renderer.c

@@ -327,6 +327,7 @@ struct wlr_renderer *wlr_pixman_renderer_create(void) {
 
 	wlr_log(WLR_INFO, "Creating pixman renderer");
 	wlr_renderer_init(&renderer->wlr_renderer, &renderer_impl, WLR_BUFFER_CAP_DATA_PTR);
+	renderer->wlr_renderer.features.output_color_transform = false;
 	wl_list_init(&renderer->buffers);
 	wl_list_init(&renderer->textures);
 

render/vulkan/renderer.c

@@ -2403,6 +2403,7 @@ struct wlr_renderer *vulkan_renderer_create_for_device(struct wlr_vk_device *dev
 
 	renderer->dev = dev;
 	wlr_renderer_init(&renderer->wlr_renderer, &renderer_impl, WLR_BUFFER_CAP_DMABUF);
+	renderer->wlr_renderer.features.output_color_transform = true;
 	wl_list_init(&renderer->stage.buffers);
 	wl_list_init(&renderer->foreign_textures);
 	wl_list_init(&renderer->textures);