Allow QQmlDebugProcess to be child of other qobjects.

Allow QQmlDebugProcess to be child of other qobjects.

Some tests when failing would leave the process running.
For example on my machine tst_qqmlinspector would hang and
restarting it would not work because the before started process was
still blocking the port.

Change-Id: I32dfb4874b18d7dcf34d0f40819b17dedd794ff3
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>