Merge topic 'FindPkgConfig-LIBRARY_PATH' into release-3.23

11c8da94d4 FindPkgConfig: Fix preservation of ENV{PKG_CONFIG_ALLOW_SYSTEM_LIBS}

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !7258