The glibc developers made the decision not to display
accented (national) characters and display question marks
instead, if the application does not initialize its locale.

While this is basically correct and I can understand this
from the glibc point of view, there is a lot of applications
that do not bother with setlocale call and as the glibc
messages are localised, they are subsequently mangled.
To fix all of the apps will take a looong time.

This change already has generated a bunch of questions
on local mailing lists.

The workaround is simple - set OUTPUT_CHARSET to desired
character set. Maybe the installer should set this in
/etc/sysconfig/i18n along with other variables (at least
optionally after confirmation, maybe there are cases where
this is not the best idea).

Reproducing:
unsetenv all LC_, LANG, OUTPUT_CHARSET env. variables,
if present

% gcc /nonexistent
gcc: /nonexistent: No such file or directory
gcc: No input files
% setenv LANG sk_SK
% gcc /nonexistent
gcc: /nonexistent: Adres?r alebo s?bor neexistuje
gcc: No input files
% setenv OUTPUT_CHARSET sk_SK
% gcc /nonexistent
gcc: /nonexistent: Adresar alebo szbor neexistuje
gcc: No input files