CellSPU: Add new directory under tests/CodeGen/CellSPU to retain tests that

aren't part of the test suite but are generally useful nonetheless, and can
be expanded later to test the backend against the actual Cell SPU system.

There's basically no other good place to put this code, so put it here for
the time being.

- vecoperations.c: Vector shuffles for all supported vector types, tests
  for v16i8 add and multiply.

llvm-svn: 60566