gl-renderer: fix leak on dmabuf image destroy

Signed-off-by: Arnaud Vrac <rawoul@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
diff --git a/libweston/gl-renderer.c b/libweston/gl-renderer.c
index da29b07..5768f05 100644
--- a/libweston/gl-renderer.c
+++ b/libweston/gl-renderer.c
@@ -337,6 +337,7 @@
 		linux_dmabuf_buffer_set_user_data(image->dmabuf, NULL, NULL);
 
 	wl_list_remove(&image->link);
+	free(image);
 }
 
 static const char *