permissions on bcopy.s?

[Stephen Weeks]

> Where does bcopy.s come from?  

It came from the PolySpace guys.  It is not used, but I didn't want
their code to disappear.

> I see that it uses the sfence instruction, which I don't think
> exists on all CPUs (it is listed as requires SSE). 

I think it only runs if the processor_has_sse2.

> (Also the file has execute permissions.) 

I don't know how to fix this.  I think you can just change it in the
repository.

> It is really designed only for multi-CPU
> apps sharing memory, so it seems a bit strange that we use it.

> Yikes: I see code in the MLton startup to read if we have SSE from
> /proc/cpuinfo.  What are we using this stuff for?

Yeah, that's from them as well, but it's #if'ed out.  I just copied it
over so it wasn't lost.