According to QUIP-18 [1], all build system files should be
BSD-3-Clause
[1]: https://contribute.qt-project.org/quips/18
Task-number: QTBUG-121787
Change-Id: I06880d91e4c6f8d7a92d249f3d216b2bc82fdeed
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit d478ca528511fcaa95491bcedaa259b2f6c5e727)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>