Add a minor modification to LeastSquare.cpp due to GSL-2.7

cpp/utility/mathops/LeastSquare.cpp

@@ -71,7 +71,9 @@ void OW3DSeakeeping::leastSquareFitting(
     status = gsl_multifit_test_delta(s->dx, s->x, 1e-4, 1e-4);
   } while (status == GSL_CONTINUE && iter < 1000);
 
-  gsl_multifit_covar(s->J, 0.0, covar);
+  gsl_matrix *J = gsl_matrix_alloc(n, p);
+  gsl_multifit_fdfsolver_jac(s, J);
+  gsl_multifit_covar(J, 0.0, covar);
 
 #define FIT(i) gsl_vector_get(s->x, i)
 #define ERR(i) sqrt(gsl_matrix_get(covar, i, i))