[Bench] Add computeJacobiansTimeVariation to the bench

benchmark/timings.cpp

@@ -131,6 +131,13 @@ int main(int argc, const char ** argv)
       computeJacobians(model,data,qs[_smooth]);
     }
   std::cout << "Jacobian = \t"; timer.toc(std::cout,NBT);
+  
+  timer.tic();
+  SMOOTH(NBT)
+  {
+    computeJacobiansTimeVariation(model,data,qs[_smooth],qdots[_smooth]);
+  }
+  std::cout << "Jacobian Time Variation = \t"; timer.toc(std::cout,NBT);
 
   timer.tic();
   SMOOTH(NBT)