wayland/buffer: Trace instrument buffer-attach

While browsing sysprof profiling reports, I saw surface-commit taking
significant times sometimes; trace attach too, to see whether such
things are due to e.g. texture uploads.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1616>

src/wayland/meta-wayland-buffer.c

@@ -530,6 +530,8 @@ meta_wayland_buffer_attach (MetaWaylandBuffer  *buffer,
 {
   g_return_val_if_fail (buffer->resource, FALSE);
 
+  COGL_TRACE_BEGIN_SCOPED (MetaWaylandBufferAttach, "WaylandBuffer (attach)");
+
   if (!meta_wayland_buffer_is_realized (buffer))
     {
       /* The buffer should have been realized at surface commit time */