sysinfo vs sysconf

[Stephen Weeks]

> sysconf() doesn't have an entry for swap.  Note, sysconf is much faster, and
> the sysinfo() is slowing us down a bit on really short-running programs.
> On the other hand, the swap is nice to know about I guess.
> I hadn't seen the mem_unit thing before, but the kernel code does try to do
> something.  From what it does, I bet it would still fail, but at least it will
> handle 2-4 gig this way.

That's good enough for me.  I checked in a fix to setMemInfo that uses
sysinfo.

That's the last thing on my todo for all of these GC changes to handle
large arrays and up to 4G of memory.  Those of you that have large
machines, please bash away, as there are certainly still bugs.