Fix a couple of issue with the vectorization. In particular, default ei_p* functions

are provided to handle not suported types seemlessly.

Added a generic null-ary expression with null-ary functors. They replace
Zero, Ones, Identity and Random.

Eigen/src/Core/Block.h

@@ -71,7 +71,7 @@ struct ei_traits<Block<MatrixType, BlockRows, BlockCols> >
                       || (ColsAtCompileTime != Dynamic && MatrixType::ColsAtCompileTime == Dynamic))
                       ? ~LargeBit
                       : ~(unsigned int)0,
-    Flags = MatrixType::Flags & FlagsMaskLargeBit & ~VectorizableBit,
+    Flags = MatrixType::Flags & FlagsMaskLargeBit & ~(VectorizableBit | Like1DArrayBit),
     CoeffReadCost = MatrixType::CoeffReadCost
   };
 };