Update Eigen to the latest stable release, 3.2.2

./Eigen/src/Core/util/NonMPL2.h is left untouched, so that
usage of non MPL2 code is disabled.

Change-Id: I86fc9257b3c30d0ca15b268d4ef07bf038bba7ca
diff --git a/lapack/cholesky.cpp b/lapack/cholesky.cpp
index 604fa43..ea3bc12 100644
--- a/lapack/cholesky.cpp
+++ b/lapack/cholesky.cpp
@@ -26,8 +26,8 @@
   Scalar* a = reinterpret_cast<Scalar*>(pa);
   MatrixType A(a,*n,*n,*lda);
   int ret;
-  if(UPLO(*uplo)==UP) ret = internal::llt_inplace<Scalar, Upper>::blocked(A);
-  else                ret = internal::llt_inplace<Scalar, Lower>::blocked(A);
+  if(UPLO(*uplo)==UP) ret = int(internal::llt_inplace<Scalar, Upper>::blocked(A));
+  else                ret = int(internal::llt_inplace<Scalar, Lower>::blocked(A));
 
   if(ret>=0)
     *info = ret+1;