Only one process can attach to the system wide application output
buffer. Re-add checks that makes sure we don't try to attach
as second one.

Change-Id: Ic50b43b8d0ac58d792075b59ecb3e490fdb75df8
Reviewed-on: http://codereview.qt.nokia.com/827


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>