[tree-ssa] Fix variables getting out of their scope

[Zdenek Dvorak]

Hello,

> >>Not really -- not every BIND_EXPR has a BIND_EXPR_BLOCK.
> >>
> >Ah, yes.  In that case the patch is OK.
> >
> 
> Actually, Zdenek, if it's not too much trouble, could you update 
> bsi_move_* to make it reset the scope on the moved statement to the 
> proper new scope?
> That way when you move a statement, you can just call fixup_var_scopes 
> on the defined variable with the old scope, and it'll do the right 
> thing.

Calling it for all defs and uses seems more correct to me in this case,
but otherwise this should work.  I will do it tomorrow.

Zdenek