Fix two segaults in test code.

Thanks to Sergey Popov for reporting this.

Change-Id: Ib5124a90fc42ae9d7295c04d51a5dd8d16250504

internal/ceres/evaluator_test.cc

@@ -818,8 +818,8 @@ class StaticEvaluateTest : public ::testing::Test {
                        expected_gradient,
                        expected_jacobian,
                        cost,
-                       &residuals[0],
-                       &gradient[0],
+                       residuals.size() > 0 ? &residuals[0] : NULL,
+                       gradient.size() > 0 ? &gradient[0] : NULL,
                        dense_jacobian.data());
   }
 

internal/ceres/levenberg_marquardt_strategy_test.cc

@@ -119,7 +119,7 @@ TEST(LevenbergMarquardtStrategy, CorrectDiagonalToLinearSolver) {
   jacobian(0,2) = 100.0;
 
   double residual = 1.0;
-  double x[2];
+  double x[3];
   DenseSparseMatrix dsm(jacobian);
 
   TrustRegionStrategy::Options options;