Regression due to tree loop opt / expand weirdness

[Paolo Bonzini]

> expander seems to expect that pointer is first casted to integer
> of the same size, and then to the target type (at least this is the way
> such a cast is translated by C frontend).  This intermediate cast seems
> superfluous to me (and to folder, apparently); fixing expand so that
> it does not have such a weird restriction is IMHO the right way
> (although it of course would not be hard to persuade fold_convert to
> produce the extra cast).

Surely makes sense, but this is not what your patch to expand_binop did.

Paolo