glocalfile: Don’t define unsupported copy vfunc
glocalfile: Don’t define unsupported copy vfunc

The caller assumes that an unimplemented vfunc means that copying is
unsupported (and falls back to its internal copy implementation), so
there’s no point in implementing the vfunc just to unconditionally
return `G_IO_ERROR_NOT_SUPPORTED`.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib