gh-108765: Python.h no longer includes <ctype.h> (#108831)

Remove <ctype.h> in C files which don't use it; only sre.c and
_decimal.c still use it.

Remove _PY_PORT_CTYPE_UTF8_ISSUE code from pyport.h:

* Code added by commit b5047fd019
  in 2004 for MacOSX and FreeBSD.
* Test removed by commit 52ddaefb6b
  in 2007, since Python str type now uses locale independent
  functions like Py_ISALPHA() and Py_TOLOWER() and the Unicode
  database.

Modules/_sre/sre.c replaces _PY_PORT_CTYPE_UTF8_ISSUE with new
functions: sre_isalnum(), sre_tolower(), sre_toupper().

Remove unused includes:

* _localemodule.c: remove <stdio.h>.
* getargs.c: remove <float.h>.
* dynload_win.c: remove <direct.h>, it no longer calls _getcwd()
  since commit fb1f68ed7c (in 2001).

Python/errors.c

@@ -10,7 +10,6 @@
 #include "pycore_sysmodule.h"     // _PySys_Audit()
 #include "pycore_traceback.h"     // _PyTraceBack_FromFrame()
 
-#include <ctype.h>
 #ifdef MS_WINDOWS
 #  include <windows.h>
 #  include <winbase.h>