[foreign] Handling pointers with special (negative) values

[Florian Weimer]

* Jorn Vernee:

> The constructor of BoundedMemoryRegion checks to make sure that the
> base (i.e. `min`) is not smaller than 0, but in this case it is, so an
> IAE is thrown [4].

Isn't the check simply incorrect?  I was under the impression that
Solaris has userspace pointers in the upper region of the address space
on x86-64 (i.e, where the 17 or so most significant bits are set).

Thanks,
Florian