To not disturb the qmake build we kept syncqt.pl in <src>/bin but
installed it to libexec. This is not necessary anymore.
This also removes the need for having syncqt.pl in both, bin and libexec
in the build dir of qtbase.
Pick-to: 6.1
Fixes: QTBUG-91076
Change-Id: I44b014ea41e3f00c420e02fd5c76f11169340b8c
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
