Merge topic 'find_package-empty-roots'

adfb0623cb find_package: Fix assertion failure on empty sysroots
1c6cecdce9 cmFindPackageCommand: Fix searching a root path as a prefix

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !10113