Fix compilation when defaulting to row-major

unsupported/Eigen/src/IterativeSolvers/GMRES.h

diff --git a/unsupported/Eigen/src/IterativeSolvers/GMRES.h b/unsupported/Eigen/src/IterativeSolvers/GMRES.h
index 517035c..5a82b0d 100644
--- a/unsupported/Eigen/src/IterativeSolvers/GMRES.h
+++ b/unsupported/Eigen/src/IterativeSolvers/GMRES.h
@@ -62,7 +62,7 @@
   typedef typename Dest::RealScalar RealScalar;
   typedef typename Dest::Scalar Scalar;
   typedef Matrix < Scalar, Dynamic, 1 > VectorType;
-  typedef Matrix < Scalar, Dynamic, Dynamic > FMatrixType;
+  typedef Matrix < Scalar, Dynamic, Dynamic, ColMajor> FMatrixType;
 
   RealScalar tol = tol_error;
   const Index maxIters = iters;