PATCH: Support MIPS II

[Benjamin Kosnik]

> I have been using this patch for a while.

... it was rejected the first time, and will be rejected this time too,
as it's the exact same patch.

Since it's the style a la mode, I'll also post what I posted six months
ago. 

You'll need to work with Eric Christo or whoever the MIPS maintainer is
to clean up the MIPS configure files. Instead of including one file for
all MIPS targets, and then inside of atomicity.h switching if atomic ops
are supported, I'd rather the mips targets that can hack atomic ops
figure themselves out, so that configure.target has:

+   mips-that-can-hack-it*)
+     cpu_include_dir=config/cpu/mips

else, default to generic. 

Any clearer the second time around?

-benjamin