GNAT and ISO 10646 (UTF) characters

[Georg Bauhaus <rm-host.bauhaus@maps.futureapps.de>]

Using -gnatW8 and -gnati8 works just fine when
an input file is using international characters.

Gnatstub does not seem to know about the same international
characters, though.  Or have I just missed the options
I should specify?

Some hodgepodge source text (encoded using UTF-8) for the
sake of an example (with apologies to the French):

package Largeur is

    type Metre is delta 0.001 digits 9 range 0.0 .. 10_000.0;

    function Imprimé (C : Character) return Metre;

end Largeur;