[PATCH]Add JFFS2 eraseblock header support

[zhao forrest]

> > > 6 new JFFS2 binary, when mounting an old JFFS2 image, will reject
> > > mounting unless the old JFFS2 image doesn't use 1:N(N>1)mapping.
> >
> > I wouldn't waste code on this.
>I would just reject mounting old images as well.
>
For trying to keep compatibility, I think there's no reason for new 
JFFS2 binary to reject mounting old JFFS2 image(with clean marker) if
this image use 1:1 mapping. So I'd insist on this. Does it make sense
to you?
In fact I didn't waste many code on this, it's only a little code
for it :)

Thanks,
Forrest