Merge topic 'use-triggers-instead-of-ldconfig-calls'

302a645d73 CPack/DEB: use `triggers` instead of legacy postXXX scripts for `ldconfig`
f461382d42 CPack/DEB: rename variable w/ result of `dpkg` find to match other vars
8a8bceda98 CPack/DEB: rename internal variable

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !11779