https://ci.appveyor.com/project/denik/gevent/builds/32220510/job/wsqay6l44eygunvf#L499
       Creating library build\temp.win32-2.7\Release\build\temp.win32-2.7\Release\_corecffi.pypy-73.lib and object build\temp.win32-2.7\Release\build\temp.win32-2.7\Release\_corecffi.pypy-73.exp
500    gevent.libuv._corecffi.obj : error LNK2019: unresolved external symbol __imp__PyPyObject_Free referenced in function _gevent_realloc
501    gevent.libuv._corecffi.obj : error LNK2019: unresolved external symbol __imp__PyPyGILState_Ensure referenced in function _gevent_realloc
502    gevent.libuv._corecffi.obj : error LNK2019: unresolved external symbol __imp__PyPyGILState_Release referenced in function _gevent_realloc
503    gevent.libuv._corecffi.obj : error LNK2019: unresolved external symbol __imp__PyPyObject_Realloc referenced in function _gevent_realloc
504    build\lib.win32-2.7\gevent\libuv\_corecffi.pypy-73.pyd : fatal error LNK1120: 4 unresolved externals
505    error: command 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\link.exe' failed with exit status 1120
506    ---------