add 'extern' to pygetopt.h symbols, so then don't end up in comdat (#4909)

bpo-32264

Include/internal/pygetopt.h

 #ifndef Py_INTERNAL_PYGETOPT_H
 #define Py_INTERNAL_PYGETOPT_H
 
-int _PyOS_opterr;
-int _PyOS_optind;
-wchar_t *_PyOS_optarg;
+extern int _PyOS_opterr;
+extern int _PyOS_optind;
+extern wchar_t *_PyOS_optarg;
 
-void _PyOS_ResetGetOpt(void);
+extern void _PyOS_ResetGetOpt(void);
 
 typedef struct {
     const wchar_t *name;
@@ -13,7 +13,7 @@ typedef struct {
     int val;
 } _PyOS_LongOption;
 
-int _PyOS_GetOpt(int argc, wchar_t **argv, wchar_t *optstring,
-                 const _PyOS_LongOption *longopts, int *longindex);
+extern int _PyOS_GetOpt(int argc, wchar_t **argv, wchar_t *optstring,
+                        const _PyOS_LongOption *longopts, int *longindex);
 
 #endif /* !Py_INTERNAL_PYGETOPT_H */