There are a couple of possible runtime errors that could happen before
the state was changed to QProcess::Starting. This aligns the Unix code
with Windows, which has the state transition at the top, and with the
documentation which says we will enter QProcess::Starting state.
Complements commit 956b249528, repeating
what it did for Unix (removing the overwriting of the error message that
openChannel() sets) on Windows. We also need to ensure cleanup() is
always called.
Pick-to: 6.6 6.7
Change-Id: I76ffba14ece04f24b43efffd17aafdd47f908bf1
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>