Remove timing using the OpenMP timers

Since ADOL-C is not multi-threaded we will not be using OpenMP
in the foreseeable future.  And on a single-threaded code the
OpenMP timer and the Dune timer return the same values anyway.

[[Imported from SVN: r9431]]

dune/gfe/riemanniantrsolver.cc

@@ -240,21 +240,16 @@ void RiemannianTrustRegionSolver<GridType,TargetSpace>::solve()
 
         if (recomputeGradientHessian) {
 
-            double oldClock = omp_get_wtime();
-
             assembler_->assembleGradient(x_, rhs);
             rhs *= -1;        // The right hand side is the _negative_ gradient
             std::cout << "gradient assembly took " << gradientTimer.elapsed() << " sec." << std::endl;
-            std::cout << "gradient assembly took " << (omp_get_wtime() - oldClock) << " sec." << std::endl;
             gradientTimer.reset();
-            oldClock = omp_get_wtime();
 
             assembler_->assembleMatrix(x_,
                                        *hessianMatrix_,
                                        i==0    // assemble occupation pattern only for the first call
                                        );
             std::cout << "hessian assembly took " << gradientTimer.elapsed() << " sec." << std::endl;
-            std::cout << "hessian assembly took " << (omp_get_wtime() - oldClock) << " sec." << std::endl;
             recomputeGradientHessian = false;
         }