Re-revert "Delay creation of the process manager"

Re-revert "Delay creation of the process manager"

This reverts commit daba2c507ad42c66dafa6a29cffa94e9641e0c58,
re-applying commit d9c06bf25210b3d0b31ee6126e57bcb82c292da1, because
the change was accidentally brought back in commit
eae8fb85997d82ecec0743ba3e470681129bff41.

There's a potential deadlock when a QProcess is created while a
QCoreApplication is instantiated but never executed, or if the main
thread waits() for the child thread.

Task-number: QTBUG-27260
Change-Id: I9e0fdc0341b3063de90979377bac35f2a827b260
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>