2ae3012fd5
The pointer returned by cogl_color_copy() was not stored anywhere and
the allocation it was pointing to got leaked. However we also don't need
to use that function here and can just copy the struct values directly.
Fixes: dc52ccc75 ("cleanup: Port from ClutterColor to CoglColor")
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3884>