Merge topic 'cmuvprocesschain-spawn-result'

891b60d691 cmUVProcessChain: Add Status::SpawnResult field
5be0cd9f3c cmUVProcessChain: Manually create pipes between processes
bb5ec5c9b4 cmUVProcessChain: Do some internal refactoring

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !8542