I expected more users of _Py_wstat(), but in practice it's only used by
Modules/getpath.c. Move the function because it's not needed on Windows.
Windows uses PC/getpathp.c which uses the Win32 API (ex: GetFileAttributesW())
not the POSIX API.
EINTR error and special cases for Windows.
These functions now truncate the length to PY_SSIZE_T_MAX to have a portable
and reliable behaviour. For example, read() result is undefined if counter is
greater than PY_SSIZE_T_MAX on Linux.
* _Py_open() now raises exceptions on error. If open() fails, it raises an
OSError with the filename.
* _Py_open() now releases the GIL while calling open()
* Add _Py_open_noraise() when _Py_open() cannot be used because the GIL is not
held
Declarations of Windows-specific auxilary functions need Windows types
from windows.h. Instead of including windows.h in Python.h and making
it available to all Windows users, it is simpler and safer just move
declarations to the single file that needs them.
_Py_char2wchar() callers usually need the result size in characters. Since it's
trivial to compute it in _Py_char2wchar() (O(1) whereas wcslen() is O(n)), add
an option to get it.
* Don't define _Py_wstat() on Windows, Windows has its own _wstat() function
with a different API (the stat buffer has another type)
* Include windows.h
* _Py_fopen() and _Py_stat() come from Python/import.c
* (_Py)_wrealpath() comes from Python/sysmodule.c
* _Py_char2wchar(), _Py_wchar2char() and _Py_wfopen() come from Modules/main.c
* (_Py)_wstat(), (_Py)_wgetcwd(), _Py_wreadlink() come from Modules/getpath.c
