fix a bug that cannot find the QGLViewer library path.
fix a bug that cannot find the QGLViewer library path.

ShudaLi/rgbd_mapping_and_relocalisation,ShudaLi/rgbd_mapping_and_relocalisation,ShudaLi/rgbd_mapping_and_relocalisation,Mavericklsd/rgbd_mapping_and_relocalisation,ShudaLi/rgbd_mapping_and_relocalisation,ShudaLi/rgbd_mapping_and_relocalisation