title: Install OpenCV to use with PyPy
body: <p>I am trying to run OpenCV with PyPy, I tried everything to make it work, but so far I couldn't. Tried downloading opencv-python from its github repository (<a href="https://github.com/skvark/opencv-python" rel="nofollow noreferrer">https://github.com/skvark/opencv-python</a>) and then running setup.py myself, but it gives me this error:</p>
  
  <pre><code>Traceback (most recent call last):  File "C:\pypy2.7-v7.1.1-win32\site-packages\skbuild\setuptools_wrap.py", line 578, in setup
      cmkr.make(make_args, env=env)
    File "C:\pypy2.7-v7.1.1-win32\site-packages\skbuild\cmaker.py", line 481, in make
      os.path.abspath(CMAKE_BUILD_DIR())))
  
  An error occurred while building with CMake.
    Command:
      "cmake" "--build" "." "--target" "install" "--config" "Release" "--"
    Source directory:
      I:\Dropbox\project\opencv-python
    Working directory:
      I:\Dropbox\project\opencv-python\_skbuild\win32-2.7\cmake-build
  Please see CMake's output for more information.
  </code></pre>
  
  <p>Tried running the command separately, but also gives me another error:
  Error: could not load the cache.
  - Also tried some solutions for that cache error but nothing.</p>
  
  <p>I couldn't understand what was the issue, and also couldn't find any CMake output file. Any help is appreciated.</p>