BUG: check alignment of strides for byteswap

closes gh-4774
BLD: add a simple python file to build cpucaps.dll

using scons seems to fail with wine 1.6, but one only needs to run three
commands so its simpler to just put these into a script instead of
trying to debug scons.
Merge pull request #4777 from juliantaylor/byteswap-align

BUG: check alignment of strides for byteswap
Merge pull request #4781 from juliantaylor/cpucaps-build

BLD: add a simple python file to build cpucaps.dll