[istl][multitype] add missing includes

dune/istl/multitypeblockmatrix.hh

@@ -5,6 +5,8 @@
 
 #include <cmath>
 #include <iostream>
+#include <tuple>
+#include <dune/common/std/constexpr.hh>
 
 #include "istlexception.hh"
 

dune/istl/multitypeblockvector.hh

@@ -9,6 +9,7 @@
 
 #include <dune/common/dotproduct.hh>
 #include <dune/common/ftraits.hh>
+#include <dune/common/std/constexpr.hh>
 
 #include "istlexception.hh"
 

dune/istl/test/multitypeblockmatrixtest.cc

@@ -43,7 +43,6 @@ int main(int argc, char** argv) try
 
   MultiTypeBlockMatrix<RowType0,RowType1> multiMatrix;
 
-  //fusion::at_c<0>(multiMatrix)[_0].setSize(3,3);
   multiMatrix[_0][_0].setSize(3,3);
   multiMatrix[_0][_1].setSize(3,2);
   multiMatrix[_1][_0].setSize(2,3);
@@ -210,4 +209,4 @@ catch (std::exception& e)
 {
   std::cerr << "Unknown exception encountered!" << std::endl;
   return 3;
-}
\ No newline at end of file
+}