Get rid of include directives inside namespace blocks (bug #339).

Eigen/src/Core/MapBase.h

@@ -30,6 +30,7 @@
       EIGEN_STATIC_ASSERT((int(internal::traits<Derived>::Flags) & LinearAccessBit) || Derived::IsVectorAtCompileTime, \
                           YOU_ARE_TRYING_TO_USE_AN_INDEX_BASED_ACCESSOR_ON_AN_EXPRESSION_THAT_DOES_NOT_SUPPORT_THAT)
 
+namespace Eigen { 
 
 /** \class MapBase
   * \ingroup Core_Module
@@ -251,5 +252,6 @@ template<typename Derived> class MapBase<Derived, WriteAccessors>
     using Base::Base::operator=;
 };
 
+} // end namespace Eigen
 
 #endif // EIGEN_MAPBASE_H