Initialize inner_iterations_were_useful_ correctly.

This variable should be initialized before the decision to
perform inner iterations are performed.

Change-Id: Ic80e2d5284ecc67eaed1859be009b1a4d18bf76b

internal/ceres/trust_region_minimizer.cc

diff --git a/internal/ceres/trust_region_minimizer.cc b/internal/ceres/trust_region_minimizer.cc
index 7a4a775..8d4407b 100644
--- a/internal/ceres/trust_region_minimizer.cc
+++ b/internal/ceres/trust_region_minimizer.cc
@@ -469,6 +469,7 @@
 // point, and if the optimization is successful, candidate_x_ will be
 // updated with the optimized parameters.
 void TrustRegionMinimizer::DoInnerIterationsIfNeeded() {
+  inner_iterations_were_useful_ = false;
   if (!inner_iterations_are_enabled_ ||
       candidate_cost_ >= std::numeric_limits<double>::max()) {
     return;