Patchset R600: selectc_cc lowering improvements

[Tom Stellard]

Hi,

The attached patches improve select_cc lowering in the R600 backend and
produce more efficient code in some cases.  Patches 1 and 2 are
bug fixes in the core LLVM libraries, which I have also sent to the list as
separate patches.  They are included here merely for convenience.

Please review.

Thanks,
Tom