CellSPU:

- Fix (brcond (setq ...)) bug, where BRNZ should have been used vice BRZ.
- Kill unused/unnecessary nodes in SPUNodes.td
- Beef out the i64operations.c test harness to use a lot of unaligned
  loads, test loops and LLVM loop/basic block optimizations; run the
  test harness successfully on real Cell hardware.

llvm-svn: 61664