add missing header guards under timing/ and examples/

examples/SFMdata.h

@@ -22,6 +22,8 @@
  * Passing function argument allows to specificy an initial position, a pose increment and step count.
  */
 
+#pragma once
+
 // As this is a full 3D problem, we will use Pose3 variables to represent the camera
 // positions and Point3 variables (x, y, z) to represent the landmark coordinates.
 // Camera observations of landmarks (i.e. pixel coordinates) will be stored as Point2 (x, y).

timing/timeSFMBAL.h

@@ -16,6 +16,8 @@
  * @date    July 5, 2015
  */
 
+#pragma once
+
 #include <gtsam/sfm/SfmData.h>
 #include <gtsam/slam/dataset.h>
 #include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>