Merge topic 'find_package-stack' into release-4.3

1b946dfbfe Merge branch 'backport-4.2-find_package-stack' into find_package-stack
e8ae3645db Merge branch 'backport-4.2-find_package-stack' into find_package-stack
aae02ee60a find_package: Share package information among copies of package stack
a789c21100 Merge branch 'backport-4.2-find_package-stack' into find_package-stack
9387988626 find_package: Save package information only after successfully loading it
561ece2407 cmFindPackageStack: Restore pure value semantics
e935ed22fb find_package: Share package information among copies of package stack
5aa649d5f6 find_package: Save package information only after successfully loading it
...

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !11887