Clean up compiler warning exposed by GCC's -Wall option: make sure

Python.h is included before standard headers since we set _GNU_SOURCE
there.  This ensures that strdup() is prototyped.

Modules/_localemodule.c

@@ -9,6 +9,8 @@ This software comes with no warranty. Use at your own risk.
 
 ******************************************************************/
 
+#include "Python.h"
+
 #include <stdio.h>
 #include <errno.h>
 #include <locale.h>
@@ -16,8 +18,6 @@ This software comes with no warranty. Use at your own risk.
 #include <limits.h>
 #include <ctype.h>
 
-#include "Python.h"
-
 #if defined(MS_WIN32)
 #define WINDOWS_LEAN_AND_MEAN
 #include <windows.h>