Issue #23152: Move declarations back to posixmodule.c.

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.

Include/fileutils.h

@@ -42,10 +42,6 @@ struct _Py_stat_struct {
     int st_ctime_nsec;
     unsigned long st_file_attributes;
 };
-
-PyAPI_FUNC(void) _Py_time_t_to_FILE_TIME(time_t, int, FILETIME *);
-PyAPI_FUNC(void) _Py_attribute_data_to_stat(BY_HANDLE_FILE_INFORMATION *,
-                                            ULONG, struct _Py_stat_struct *);
 #else
 #  define _Py_stat_struct stat
 #endif

Modules/posixmodule.c

@@ -372,6 +372,12 @@ static int win32_can_symlink = 0;
 
 #define DWORD_MAX 4294967295U
 
+#ifdef MS_WINDOWS
+/* defined in fileutils.c */
+PyAPI_FUNC(void) _Py_time_t_to_FILE_TIME(time_t, int, FILETIME *);
+PyAPI_FUNC(void) _Py_attribute_data_to_stat(BY_HANDLE_FILE_INFORMATION *,
+                                            ULONG, struct _Py_stat_struct *);
+#endif
 
 #ifdef MS_WINDOWS
 static int