[PATCH 6/9] Use proper membar instructions on SPARC

[Matt Turner]

>> What you want to check for is __sparc_v9__
>
> That's not going to be CPP defined either, unfortunately.
>
> I really think, based upon this, that the hard-coded opcodes have to
> stay.  It's the only way to cover all cases.

If that's the case, this patch can be ignored.

Does the hard-coded opcode account for the branch misprediction
errata? Does it need to?

I assume it's a write barrier, and if so I'd prefer to change the name
of the macro from barrier() to write_mem_barrier() to match with the
others.

Matt