Fix some compiler warnings.

Reported by Richard Trieu.

Change-Id: I202b7a7df09cc19c92582d276ccf171edf88a9fb

internal/ceres/gradient_checker_test.cc

diff --git a/internal/ceres/gradient_checker_test.cc b/internal/ceres/gradient_checker_test.cc
index d2ce6e3..1c01df0 100644
--- a/internal/ceres/gradient_checker_test.cc
+++ b/internal/ceres/gradient_checker_test.cc
@@ -111,8 +111,8 @@
   }
 
  private:
-  bool return_value_;
   int arity_;
+  bool return_value_;
   vector<vector<double> > a_;  // our vectors.
 };
 
@@ -382,13 +382,9 @@
   Eigen::Vector3d param0(1.0, 2.0, 3.0);
   Eigen::Vector2d param1(4.0, 5.0);
 
-  int const arity = 2;
-  const int dim[2] = {3, 2};
-
   cost_function.AddParameter(j0);
   cost_function.AddParameter(j1);
 
-  int const num_parameters = 2;
   std::vector<int> parameter_sizes(2);
   parameter_sizes[0] = 3;
   parameter_sizes[1] = 2;