Fix detection of SSE2 with MSVC.
Fix detection of SSE2 with MSVC.

Zefz/eigen,toastedcrumpets/eigen,cjntaylor/eigen,TSC21/Eigen,TSC21/Eigen,ritsu1228/eigen,pasuka/eigen,pasuka/eigen,Zefz/eigen,ROCmSoftwarePlatform/hipeigen,cjntaylor/eigen,pthulhu/eigen,pthulhu/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,pasuka/eigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,toastedcrumpets/eigen,toastedcrumpets/eigen,pthulhu/eigen,TSC21/Eigen,pasuka/eigen,cjntaylor/eigen,cjntaylor/eigen,Zefz/eigen,ritsu1228/eigen,TSC21/Eigen,ritsu1228/eigen,toastedcrumpets/eigen,ROCmSoftwarePlatform/hipeigen,pthulhu/eigen,Zefz/eigen,ritsu1228/eigen,pthulhu/eigen