Attempt to add Haswell support (using sandybridge optimizations)

I tried to get OpenBLAS to work on my Haswell machine without having to define TARGET explicitly. This defines A couple Haswell CPUs as `CPUTYPE_SANDYBRIDGE`. This seems to be detected correctly (e.g., `config.h` is generated with `#define SANDYBRIDGE`), but that isn't sufficient to get this to work.

What am I missing here?