Various minor fixes.

1. Unused variable warnings and fixes.
2. Minor documentation update.

Change-Id: I815588a5806df1030a7c8750f4fb594c503f8998
diff --git a/internal/ceres/dogleg_strategy_test.cc b/internal/ceres/dogleg_strategy_test.cc
index 9e2ed9f..24c526e 100644
--- a/internal/ceres/dogleg_strategy_test.cc
+++ b/internal/ceres/dogleg_strategy_test.cc
@@ -206,10 +206,7 @@
   DoglegStrategy strategy(options_);
   TrustRegionStrategy::PerSolveOptions pso;
 
-  TrustRegionStrategy::Summary summary = strategy.ComputeStep(pso,
-                                                              jacobian_.get(),
-                                                              residual_.data(),
-                                                              x_.data());
+  strategy.ComputeStep(pso, jacobian_.get(), residual_.data(), x_.data());
 
   // Check if the basis is orthonormal.
   const Matrix basis = strategy.subspace_basis();
@@ -288,4 +285,3 @@
 
 }  // namespace internal
 }  // namespace ceres
-