Replace Eigen type metaprogramming with corresponding std types and make use of alias templates

Eigen/src/StlSupport/details.h

@@ -52,11 +52,11 @@ namespace Eigen {
   // in std::vector::resize(size_t s,T x) won't be aligned and generate an error
   // even if this function is never called. Whence this little wrapper.
 #define EIGEN_WORKAROUND_MSVC_STL_SUPPORT(T) \
-  typename Eigen::internal::conditional< \
+  Eigen::std::conditional_t< \
     Eigen::internal::is_arithmetic<T>::value, \
     T, \
     Eigen::internal::workaround_msvc_stl_support<T> \
-  >::type
+  >
 
   namespace internal {
   template<typename T> struct workaround_msvc_stl_support : public T