fold-const.c (extract_array_ref): Handle more cases, do some useful canonicalization of the base.

        * fold-const.c (extract_array_ref): Handle more cases,
        do some useful canonicalization of the base.
        (fold_binary): Explicitly deal with arrays of zero-sized
        structures during folding of &a[i] == &a[j].

        * gcc.dg/tree-ssa/foldaddr-1.c: New test.

From-SVN: r100391