Failed to build `sparse_octree` and `sparse_voxels` on system with `ninja` installed

[TomCC7]

The reason is that torch will use ninja to build if it's installed and caused a header path issue. To solve the issue, replacing the line in third_party/sparse_octree/setup.py and third_party/sparse_voxels/setup.py

    cmdclass={
        'build_ext': BuildExtension
    }

with

    cmdclass={
        'build_ext': BuildExtension.with_options(use_ninja=False)
    }