parseline() can call _XimParseStringFile() which can call parseline()
which can call _XimParseStringFile() which can call parseline() ....
eventually causing recursive stack overflow and crash.

Limit is set to a include depth of 100 files, which should be enough
for all known use cases, but could be adjusted later if necessary.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Matthieu Herrb <matthieu.herrb@laas.fr>
Signed-off-by: Julien Cristau <jcristau@debian.org>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>