D5766: Change default pkgconfig install path for FreeBSD

[Tobias C. Berner]

tcberner marked an inline comment as done.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D5766

To: tcberner, #freebsd, apol, kfunk
Cc: kfunk, #frameworks, #build_system