Port Ceres to Windows

This is a preliminary, but full, port of Ceres to Windows.
Currently all tests compile and run, with only system_test
failing to work correctly due to a path issue.

Change-Id: I4152c1588bf51ffd7f4d9401ef9759f5d28c299c

internal/ceres/linear_solver.cc

@@ -81,6 +81,7 @@ LinearSolver* LinearSolver::Create(const LinearSolver::Options& options) {
     default:
       LOG(FATAL) << "Unknown linear solver type :"
                  << options.type;
+	  return NULL;  // MSVC doesn't understand that LOG(FATAL) never returns.
   }
 }