SuiteSparse errors do not cause a fatal crash.

1. Move LinearSolverTerminationType to ceres::internal.
2. Add FATAL_ERROR as a new enum to LinearSolverTerminationType.
3. Pipe SuiteSparse errors via a LinearSolverTerminationType so
   to distinguish between fatal and non-fatal errors.
4. Update levenberg marquardt and dogleg strategies to deal
   with FATAL_ERROR.
5. Update trust_region_minimizer to terminate when FATAL_ERROR
   is encountered.
6. Remove SuiteSparse::SolveCholesky as it screws up the error
   handling.
7. Fix all clients calling SuiteSparse to handle the result of
   SuiteSparse::Cholesky correctly.
8. Remove fatal failures in SuiteSparse when symbolic factorization
   fails.
9. Fix all clients of SuiteSparse to deal with null symbolic factors.

This is a temporary fix to deal with some production problems. A more
extensive cleanup and testing regime will be put in place in a
subsequent CL.

Change-Id: I1f60d539799dd95db7ecc340911e261fa4824f92

include/ceres/types.h

@@ -159,26 +159,6 @@ enum DenseLinearAlgebraLibraryType {
   LAPACK
 };
 
-enum LinearSolverTerminationType {
-  // Termination criterion was met. For factorization based solvers
-  // the tolerance is assumed to be zero. Any user provided values are
-  // ignored.
-  TOLERANCE,
-
-  // Solver ran for max_num_iterations and terminated before the
-  // termination tolerance could be satified.
-  MAX_ITERATIONS,
-
-  // Solver is stuck and further iterations will not result in any
-  // measurable progress.
-  STAGNATION,
-
-  // Solver failed. Solver was terminated due to numerical errors. The
-  // exact cause of failure depends on the particular solver being
-  // used.
-  FAILURE
-};
-
 // Logging options
 // The options get progressively noisier.
 enum LoggingType {
@@ -479,9 +459,6 @@ bool StringToCovarianceAlgorithmType(
     string value,
     CovarianceAlgorithmType* type);
 
-const char* LinearSolverTerminationTypeToString(
-    LinearSolverTerminationType type);
-
 const char* SolverTerminationTypeToString(SolverTerminationType type);
 
 bool IsSchurType(LinearSolverType type);