Silence some MSVC warnings

Eigen/src/Core/util/Memory.h

diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index dc6cec7..3ba2348 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -296,7 +296,7 @@
   */
 template<typename T> EIGEN_DEVICE_FUNC inline T* construct_elements_of_array(T *ptr, std::size_t size)
 {
-  std::size_t i;
+  std::size_t i=0;
   EIGEN_TRY
   {
       for (i = 0; i < size; ++i) ::new (ptr + i) T;
@@ -307,7 +307,6 @@
     destruct_elements_of_array(ptr, i);
     EIGEN_THROW;
   }
-  return NULL;
 }
 
 /*****************************************************************************