Issue #13706: Fix format(int, "n") for locale with non-ASCII thousands separator
* Decode thousands separator and decimal point using PyUnicode_DecodeLocale()
(from the locale encoding), instead of decoding them implicitly from latin1
* Remove _PyUnicode_InsertThousandsGroupingLocale(), it was not used
* Change _PyUnicode_InsertThousandsGrouping() API to return the maximum
character if unicode is NULL
* Replace MIN/MAX macros by Py_MIN/Py_MAX
* stringlib/undef.h undefines STRINGLIB_IS_UNICODE
* stringlib/localeutil.h only supports Unicode
diff --git a/Objects/stringlib/undef.h b/Objects/stringlib/undef.h
index fd87e56..9310204 100644
--- a/Objects/stringlib/undef.h
+++ b/Objects/stringlib/undef.h
@@ -7,5 +7,5 @@
#undef STRINGLIB_NEW
#undef STRINGLIB_RESIZE
#undef _Py_InsertThousandsGrouping
-#undef _Py_InsertThousandsGroupingLocale
+#undef STRINGLIB_IS_UNICODE