syncqt.pl: also allow digits in upper-case macro names

The check for Q_... macros used a regex that didn't allow digits; it
thus failed to match Q_DECLARE_SHARED_NOT_MOVABLE_UNTIL_QT6().

Change-Id: I3f9339349aa21e2fea04a7f53d9d8e0903e4c65b
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>