V4: remove failing assert and fix code.

Assert failed for cases where the node’s ancestor with lowest
semi-dominator number was not the same as the parent. The test case
exemplifies this.

Task-number: QTBUG-34792
Change-Id: Ie6847b22a27211801bff7479bfcbfaf329c6005a
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Fix compilation on QNX

pthread_getattr_np is not available there, so we use the default implementation (1MB stack limit) for now.

Change-Id: Ia1f3cbbcd846998b688541c0b576ef42f22ac8b6
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
FileDialog example: remove setGeometry button

This was more of a manual test than an example: it should be possible
to set the geometry of widget-based and qml-based dialogs.  Since it
doesn't work for native dialogs let's not invite bug reports about it.

Change-Id: I43cb97bff0af932268ae541e3f812fc17a1f76ae
Reviewed-by: Liang Qi <liang.qi@digia.com>