Re: python-numpy (1.22.0-1) can't be imported

[Masamichi Hosoda <trueroad@trueroad.jp>]

> If I understand correctly, I've found the root cause of the issue.
> I've sent a pull request to numpy.
> https://github.com/numpy/numpy/pull/20874

A question is asked by NumPy if there is documentation
on the Cygwin package's Cython behavior.
https://github.com/numpy/numpy/pull/20874#issuecomment-1019442058

Does such a document exist?

One of the causes of this issue is a patch
in Cygwin's python-cython package like the one below.
It removes the `__declspec(dllexport)` attribute
from the symbols to be exported.

On the other hand, if you install Cython
by pip without using the Cygwin package,
the exported symbols have the `__declspec(dllexport)` attribute
because the patch has not been applied.

What is the purpose of removing the `__declspec(dllexport)` attribute
in this patch?
Is this to make the modules using Cython
without considering the Cygwin environment,
the module does not have the `__declspec(dllexport)` attribute
like Linux environment, works correctly?

```
--- origsrc/Cython-0.29.21/Cython/Utility/ModuleSetupCode.c	2020-07-08 23:44:39.000000000 +0200
+++ Cython/Utility/ModuleSetupCode.c	2021-01-30 08:34:37.402649500 +0100
@@ -709,7 +709,11 @@ static CYTHON_INLINE void * PyThread_tss
 /////////////// PyModInitFuncType.proto ///////////////
 
 #ifndef CYTHON_NO_PYINIT_EXPORT
-#define __Pyx_PyMODINIT_FUNC PyMODINIT_FUNC
+#ifdef __cplusplus
+#define __Pyx_PyMODINIT_FUNC extern "C" PyObject *
+#else
+#define __Pyx_PyMODINIT_FUNC PyObject *
+#endif
 
 #elif PY_MAJOR_VERSION < 3
 // Py2: define this to void manually because PyMODINIT_FUNC adds __declspec(dllexport) to it's definition.
```