[tex-live] xindy and folders with non ascii chars

[Bruno Haible]

> Karl Berry writes in
> <https://www.tug.org/pipermail/tex-live/2018-September/042413.html>:
> > Why not
> > #define VALID_FILENAME_CHAR (1)
> > ? What is gained by all these conditions?
> 
> When the user enters an invalid file name,
> 1. clisp signals an error before the file name hits the file system,
>    namely already when the Lisp pathname gets constructed,
> 2. the error message indicates the cause (remember that errors on
>    a file system can be caused by invalid file names, permission
>    problems, or even temporary issues like disk-full problems).

And 3. On some systems, really erratic things happen when you pass
file names with invalid bytes to the operating system.

Bruno