Problem with operand handling

[Richard Kenner]

    I think he was looking for the traceback froim this abort() so we can
    see where the real operand is incorrectly being added to the alias
    list...

Sorry.  This was a small enough test case that I already was able to set
a breakpoint there.

It's from compute_flow_insensitive_aliasing.  But I see something
interesting.  This is in addressable_vars and TREE_ADDRESSABLE isn't
set.  That's wrong, isn't it?