Remove ExecutionSummary from Evaluator and LinearSolver

Change-Id: If4dbaf516a8b14e0a79e1a2116ce66a99ed4a592

internal/ceres/evaluator.h

diff --git a/internal/ceres/evaluator.h b/internal/ceres/evaluator.h
index f3be38c..600feda 100644
--- a/internal/ceres/evaluator.h
+++ b/internal/ceres/evaluator.h
@@ -155,7 +155,6 @@
   // The number of residuals in the optimization problem.
   virtual int NumResiduals() const = 0;
 
-  virtual ExecutionSummary ExecutionSummary() const { return ExecutionSummary(); }
 };
 
 }  // namespace internal

internal/ceres/linear_solver.h

diff --git a/internal/ceres/linear_solver.h b/internal/ceres/linear_solver.h
index 6e03f60..29959d3 100644
--- a/internal/ceres/linear_solver.h
+++ b/internal/ceres/linear_solver.h
@@ -256,8 +256,6 @@
                         const PerSolveOptions& per_solve_options,
                         double* x) = 0;
 
-  virtual const ExecutionSummary ExecutionSummary() const { return ExecutionSummary(); }
-
   // Factory
   static LinearSolver* Create(const Options& options);
 };