Fix compilation errors:

  dolfin/geometry/IntersectionConstruction.cpp: In static member function ‘static std::vector<dolfin::Point> dolfin::IntersectionConstruction::intersection_segment_segment_2d(const dolfin::Point&, const dolfin::Point&, const dolfin::Point&, const dolfin::Point&)’:
  dolfin/geometry/IntersectionConstruction.cpp:442:24: error: ‘min_element’ is not a member of ‘std’; did you mean ‘tuple_element’?
    442 |   const auto it = std::min_element(oo.begin(), oo.end());
        |                        ^~~~~~~~~~~
        |                        tuple_element

  dolfin/mesh/MeshFunction.h: In member function ‘std::vector<long unsigned int> dolfin::MeshFunction<T>::where_equal(T)’:
  dolfin/mesh/MeshFunction.h:652:26: error: ‘count’ is not a member of ‘std’; did you mean ‘cout’?
    652 |     std::size_t n = std::count(_values.get(), _values.get() + _size, value);
        |                          ^~~~~
        |                          cout

Submitted upstream at https://bitbucket.org/fenics-project/dolfin/issues/1128

--- a/dolfin/geometry/IntersectionConstruction.cpp
+++ b/dolfin/geometry/IntersectionConstruction.cpp
@@ -18,7 +18,8 @@
 // First added:  2014-02-03
 // Last changed: 2017-12-12
 
+#include <algorithm>
 #include <iomanip>
 #include <dolfin/mesh/MeshEntity.h>
 #include "predicates.h"

--- a/dolfin/mesh/MeshFunction.h
+++ b/dolfin/mesh/MeshFunction.h
@@ -24,6 +24,7 @@
 #ifndef __MESH_FUNCTION_H
 #define __MESH_FUNCTION_H
 
+#include <algorithm>
 #include <map>
 #include <vector>