STYLE: use Time::printExecutionTime() method

- makes format of ExecutionTime = ... output configurable (#788)
  and reduces code clutter.

applications/utilities/postProcessing/optimisation/computeSensitivities/computeSensitivities.C

@@ -64,9 +64,7 @@ int main(int argc, char *argv[])
         }
     }
 
-    Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
-        << "  ClockTime = " << runTime.elapsedClockTime() << " s"
-        << nl << endl;
+    runTime.printExecutionTime(Info);
 
     Info<< "End" << endl;
 

src/optimisation/adjointOptimisation/adjoint/optimisation/adjointSensitivity/incompressible/adjointEikonalSolver/adjointEikonalSolverIncompressible.C

@@ -207,9 +207,7 @@ void adjointEikonalSolver::solve()
         scalar residual = daEqn.solve().initialResidual();
         Info<< "Max da " << gMax(mag(da_)()) << endl;
 
-        Info<< "ExecutionTime = " << mesh_.time().elapsedCpuTime() << " s"
-            << "  ClockTime = " << mesh_.time().elapsedClockTime() << " s"
-            << nl << endl;
+        mesh_.time().printExecutionTime(Info);
 
         // Check convergence
         if (residual < tolerance_)

src/optimisation/adjointOptimisation/adjoint/optimisation/adjointSensitivity/incompressible/adjointMeshMovementSolver/adjointMeshMovementSolverIncompressible.C

@@ -146,9 +146,7 @@ void adjointMeshMovementSolver::solve()
 
         Info<< "Max ma " << gMax(mag(ma_)()) << endl;
 
-        Info<< "ExecutionTime = " << mesh_.time().elapsedCpuTime() << " s"
-            << "  ClockTime = " << mesh_.time().elapsedClockTime() << " s"
-            << nl << endl;
+        mesh_.time().printExecutionTime(Info);
 
         // Check convergence
         if (residual < tolerance_)