Update to compile with stricter gcc checks.

Change-Id: Iecb37cbe7201a4d4f42b21b427fa1d35d0183b1b

include/ceres/dynamic_autodiff_cost_function.h

diff --git a/include/ceres/dynamic_autodiff_cost_function.h b/include/ceres/dynamic_autodiff_cost_function.h
index e4549c5..9ffad5e 100644
--- a/include/ceres/dynamic_autodiff_cost_function.h
+++ b/include/ceres/dynamic_autodiff_cost_function.h
@@ -123,7 +123,8 @@
     vector<Jet<double, Stride> > output_jets(num_residuals());
 
     // Make the parameter pack that is sent to the functor (reused).
-    vector<Jet<double, Stride>* > jet_parameters(num_parameter_blocks, NULL);
+    vector<Jet<double, Stride>* > jet_parameters(num_parameter_blocks,
+        static_cast<Jet<double, Stride>* >( NULL));
     int num_active_parameters = 0;
     int start_derivative_section = -1;
     for (int i = 0, parameter_cursor = 0; i < num_parameter_blocks; ++i) {