Merge topic 'findopengl-glu-include-dir'

aebebf72df FindOpenGL: Add support for a separate GLU include directory

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Acked-by: Alex <leha-bot@yandex.ru>
Merge-request: !9216