Remove an unused variable from evaluation_benchmark.cc

Change-Id: Ibc1133d0fb0ee4dd160712fb3c1c72aec54f2b08

internal/ceres/evaluation_benchmark.cc

diff --git a/internal/ceres/evaluation_benchmark.cc b/internal/ceres/evaluation_benchmark.cc
index aba2386..2f9fff0 100644
--- a/internal/ceres/evaluation_benchmark.cc
+++ b/internal/ceres/evaluation_benchmark.cc
@@ -131,7 +131,6 @@
   const BlockSparseMatrix* BlockSparseJacobianWithTranspose(
       ContextImpl* context) {
     if (!block_sparse_jacobian_with_transpose) {
-      auto regular = BlockSparseJacobian(context);
       block_sparse_jacobian_with_transpose = CreateBlockSparseJacobian(context);
       block_sparse_jacobian_with_transpose->AddTransposeBlockStructure();
     }