Rename LinearSolverTerminationType enums.

This increases clarity, drops redundant enums and makes things
cleaner all around.

Change-Id: I761f195ddf17ea6bd8e4e55bf5a72863660c4c3b
diff --git a/internal/ceres/covariance_impl.cc b/internal/ceres/covariance_impl.cc
index 1bca3c3..91f0393 100644
--- a/internal/ceres/covariance_impl.cc
+++ b/internal/ceres/covariance_impl.cc
@@ -454,7 +454,7 @@
   LinearSolverTerminationType termination_type =
       ss.Cholesky(&cholmod_jacobian_view, factor, &status);
   event_logger.AddEvent("Numeric Factorization");
-  if (termination_type != TOLERANCE) {
+  if (termination_type != LINEAR_SOLVER_SUCCESS) {
     LOG(ERROR) << "Covariance estimation failed. "
                << "CHOLMOD numeric cholesky factorization returned with: "
                << status;