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).

Include/Python.h

@@ -17,7 +17,6 @@
 
 // Include standard header files
 #include <assert.h>               // assert()
-#include <ctype.h>                // tolower()
 #include <inttypes.h>             // uintptr_t
 #include <limits.h>               // INT_MAX
 #include <math.h>                 // HUGE_VAL