Merge topic 'timeout-after-match-stop-time-behavior' into release-4.2

68beb2e514 Tests/CTestTimeoutAfterMatch: add case for stop time bug
af7427675a cmProcess: compute the timeout when needed
c6940b0dcc cmProcess: explicitly track the StopTimeout

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !11551