How to install cython package before cythonizing

[Naotoshi Seo]

Hi, I have a cython program which depends on a cython package ( https://github.com/scoder/fastrlock ) and pxd files in it.

I need to install the cython package before cythonize because my cython program depends on its pxd files.

Referring http://cython.readthedocs.io/en/latest/src/reference/compilation.html, I am trying like:

setup.py

```

from setuptools import setup

from distutils.extension import Extension

from Cython.Build import cythonize

extensions = [

    Extension("cupy.cuda.memory", ["cupy/cuda/memory.pyx"],

        include_dirs = ['/usr/local/cuda/include'],

        libraries = ['cublas', 'cuda', 'cudart', 'curand', 'cusparse', 'nvrtc', 'nvToolsExt'],

        library_dirs = ['/usr/local/cuda/lib64'])

]

ext_modules = cythonize(extensions)

install_requires = ['fastrlock>=0.3']

setup(

    name = "cupy",

    install_requires = install_requires,

    ext_modules = ext_modules,

)

```

However, this version tries to cythonize before fastrlock is installed.

How can I install cython package before cythonizing?