Fix include guard, avoid duplication

dune/solvers/computeenergy.hh

 // -*- tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 // vi: set et ts=8 sw=4 sts=4:
-#ifndef CONTACT_COMPUTE_ENERGY_HH
-#define CONTACT_COMPUTE_ENERGY_HH
+#ifndef DUNE_SOLVERS_COMPUTEENERGY_HH
+#define DUNE_SOLVERS_COMPUTEENERGY_HH
 
 #include "common/arithmetic.hh"
 
 template <class M, class V>
-double computeEnergy(const M& mat, const V& x, const V& rhs)
+double computeEnergy(const M& mat, const V& x)
 {
-    return 0.5*Arithmetic::Axy(mat,x,x) - rhs*x;
+    return 0.5*Arithmetic::Axy(mat,x,x);
 }
 
 template <class M, class V>
-double computeEnergy(const M& mat, const V& x)
+double computeEnergy(const M& mat, const V& x, const V& rhs)
 {
-    return 0.5*Arithmetic::Axy(mat,x,x);
+    return computeEnergy(mat,x) - rhs*x;
 }
-
 #endif