Fix compilation with old icc

Eigen/src/Core/util/Meta.h

diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 01a9647..7ecd59a 100644
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -27,9 +27,11 @@
   * we however don't want to add a dependency to Boost.
   */
 
-#if EIGEN_COMP_ICC
-typedef intptr_t IntPtr;
-typedef uintptr_t UIntPtr;
+// Only recent versions of ICC complain about using ptrdiff_t to hold pointers,
+// and older versions do not provide *intptr_t types.
+#if EIGEN_COMP_ICC>=1600
+typedef std::intptr_t  IntPtr;
+typedef std::uintptr_t UIntPtr;
 #else
 typedef std::ptrdiff_t IntPtr;
 typedef std::size_t UIntPtr;