fix bug 521: __cpuidex is not available on all architectures supported by MSVC
fix bug 521: __cpuidex is not available on all architectures supported by MSVC

cjntaylor/eigen,cjntaylor/eigen,cjntaylor/eigen,pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,cjntaylor/eigen,pthulhu/eigen,pthulhu/eigen