Fix tree-optimization/17528 and libstdc++ tests

[Daniel Berlin]

On Thu, 2004-09-16 at 21:27 -0400, Diego Novillo wrote:
> The memset-3.c failure is an ICE in tree-ssa-pre.c:
> 
> internal compiler error: tree check: expected value_handle, have addr_expr in value_insert_into_set_bitmap, at tree-ssa-pre.c:470
> 

I can't reproduce this failure (even though i haven't committed anything
that caused it, i was curious).

If you give me a backtrace, however, i may be able to solve it.
Also, can you tell me if the addr_expr in question is
is_gimple_min_invariant?

--Dan