Fix build breakage on old versions of SuiteSparse.

Change-Id: I2a061615fc374abef2ed323c298359002a6fc5f1

internal/ceres/covariance_impl.cc

diff --git a/internal/ceres/covariance_impl.cc b/internal/ceres/covariance_impl.cc
index faa0ce5..75c80bf 100644
--- a/internal/ceres/covariance_impl.cc
+++ b/internal/ceres/covariance_impl.cc
@@ -441,23 +441,23 @@
   cholmod_jacobian_view.sorted = 1;
   cholmod_jacobian_view.packed = 1;
 
-  string status;
-  cholmod_factor* factor = ss.AnalyzeCholesky(&cholmod_jacobian_view, &status);
+  string message;
+  cholmod_factor* factor = ss.AnalyzeCholesky(&cholmod_jacobian_view, &message);
   event_logger.AddEvent("Symbolic Factorization");
   if (factor == NULL) {
     LOG(ERROR) << "Covariance estimation failed. "
                << "CHOLMOD symbolic cholesky factorization returned with: "
-               << status;
+               << message;
     return false;
   }
 
   LinearSolverTerminationType termination_type =
-      ss.Cholesky(&cholmod_jacobian_view, factor, &status);
+      ss.Cholesky(&cholmod_jacobian_view, factor, &message);
   event_logger.AddEvent("Numeric Factorization");
   if (termination_type != LINEAR_SOLVER_SUCCESS) {
     LOG(ERROR) << "Covariance estimation failed. "
                << "CHOLMOD numeric cholesky factorization returned with: "
-               << status;
+               << message;
     ss.Free(factor);
     return false;
   }
@@ -506,7 +506,7 @@
     }
 
     rhs_x[r] = 1.0;
-    cholmod_dense* solution = ss.Solve(factor, rhs);
+    cholmod_dense* solution = ss.Solve(factor, rhs, &message);
     double* solution_x = reinterpret_cast<double*>(solution->x);
     for (int idx = row_begin; idx < row_end; ++idx) {
       const int c = cols[idx];