qt: don't enable internal tslib-module debugging

In Qt there are virtually hundreds of internal debug flags like
TSLIBMOUSEHANDLER_DEBUG for every module or even C++ class. There
is no reason to enable a single such flag when Qt is build with
debugging symbols and others not.

Signed-off-by: Michael Roth <mroth@nessie.de>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>