Fixed regression errors for OpencV2 (#309)

tools/CameraRGBD/main.cpp

@@ -38,7 +38,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <opencv2/highgui/highgui.hpp>
 #include <opencv2/imgproc/imgproc.hpp>
 #include <opencv2/imgproc/types_c.h>
+#if CV_MAJOR_VERSION >= 3
 #include <opencv2/videoio/videoio_c.h>
+#endif
 #include <pcl/visualization/cloud_viewer.h>
 #include <stdio.h>
 #include <signal.h>