Instantiate the QProcess object on the stack to ensure resource
cleanup and remove the QProcess * member variable.
Use qobject_cast<QProcess *>(QObject::sender()) instead
of the member variable in the helpers slots to ensure that signals
from a leaked QProcess do not interfere with other tests.
Task-number: QTBUG-47370
Change-Id: Ifc0dccb7e4b18069d236df53bccdcb6a47df6346
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>