Downgrading log status of BFGS secant condition messages.

- These messages were originally VLOG(2) and were mistakenly upgraded to
  WARNINGs when the tolerances were reduced.

Change-Id: I89dee666a09bc82cfa89b793dc0907268662f95e

internal/ceres/line_search_direction.cc

diff --git a/internal/ceres/line_search_direction.cc b/internal/ceres/line_search_direction.cc
index 5d91215..ced8da8 100644
--- a/internal/ceres/line_search_direction.cc
+++ b/internal/ceres/line_search_direction.cc
@@ -212,10 +212,10 @@
     const double kBFGSSecantConditionHessianUpdateTolerance = 1e-14;
     if (delta_x_dot_delta_gradient <=
         kBFGSSecantConditionHessianUpdateTolerance) {
-      LOG(WARNING) << "Skipping BFGS Update, delta_x_dot_delta_gradient too "
-                   << "small: " << delta_x_dot_delta_gradient << ", tolerance: "
-                   << kBFGSSecantConditionHessianUpdateTolerance
-                   << " (Secant condition).";
+      VLOG(2) << "Skipping BFGS Update, delta_x_dot_delta_gradient too "
+              << "small: " << delta_x_dot_delta_gradient << ", tolerance: "
+              << kBFGSSecantConditionHessianUpdateTolerance
+              << " (Secant condition).";
     } else {
       // Update dense inverse Hessian approximation.
 

internal/ceres/low_rank_inverse_hessian.cc

diff --git a/internal/ceres/low_rank_inverse_hessian.cc b/internal/ceres/low_rank_inverse_hessian.cc
index 6a92528..d675395 100644
--- a/internal/ceres/low_rank_inverse_hessian.cc
+++ b/internal/ceres/low_rank_inverse_hessian.cc
@@ -88,10 +88,10 @@
   const double delta_x_dot_delta_gradient = delta_x.dot(delta_gradient);
   if (delta_x_dot_delta_gradient <=
       kLBFGSSecantConditionHessianUpdateTolerance) {
-    LOG(WARNING) << "Skipping L-BFGS Update, delta_x_dot_delta_gradient too "
-                 << "small: " << delta_x_dot_delta_gradient << ", tolerance: "
-                 << kLBFGSSecantConditionHessianUpdateTolerance
-                 << " (Secant condition).";
+    VLOG(2) << "Skipping L-BFGS Update, delta_x_dot_delta_gradient too "
+            << "small: " << delta_x_dot_delta_gradient << ", tolerance: "
+            << kLBFGSSecantConditionHessianUpdateTolerance
+            << " (Secant condition).";
     return false;
   }