[AD] TRACEs in xkeyboard.c

[Elias Pschernig <elias@xxxxxxxxxx>]

Kittycat pointed out to me in #allegro that allegro.log has a lot of
info under X11. It's because xkeyboard.c writes a TRACE line for each
detected key. I think in general, it is a good idea if a library can
spit out debug info like that - because it is much easier to get
information from users who have problems (e.g. in this specific case, it
was easy to fix a problem with french number keys back then because I
had the allegro.log with all the info).

But since all other parts of Allegro have almost no runtime information
at all, and we have no way to have different debug classes and levels
(something we should add after 4.2), and user code also might use TRACE
and allegro.log, I wonder if those TRACE calls should be removed for
4.2.0..

-- 
Elias Pschernig