TODO, reenable sse?
ENH: improve performance of np.all/np.any

done by unrolling the loop once and replacing a slow movmask with a fast
pmaxb/pminb. movmask is especially slow on AMD chips.
Additionally make use of memchr on non SSE2 builds.
This requires that boolean true == 1 for any.

memchr should also be used in SSE2 builds in future when glibc >= 2.15
is available in more distributions. 2.15 performs as well our code and
we would automatically benefit from improvements made in that library
(e.g. extension to AVX)