wiki page for how to run llvm-test suite for mips using qemu user mode

I've made a wiki page for running test-suite for Mips using qemu user mode and from the tip of tree llvm.

Previous we had lots of custom scripts and modifications to llvm test-suite tip of tree to to do this but this wiki makes all of that obsolete now and we can run everything from tip of tree.

Our tool chain works very well in a cross environment and that is partly why this is possible now
(thanks to Simon Atanasyan).

I have not tested this method for any other llvm targets but no doubt there will be some issues.

For those that have not straightened out the clang driver for your target, you can adapt the alternate driver that I originally developed for Mips and later was extended and modified by Akira and Simon.

We used this to run many open source scripts that required a mature gcc compatible driver.

It's a simple python script that lets you make a python based "clang" that appears as a normal clang to other scripts.

If you add to this driver it would be great if you contribute the changes to google code.