Merge topic 'pkgc-import-system-fix' into release-4.1

d5f6cf5ba8 PkgC: Only remove system paths which are exact matches
93f77d8183 PkgC: Allow system paths during IMPORT, POPULATE

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !11078