Now that all QLinkedList uses are removed from Qt, make sure
QT_NO_LINKED_LIST is set by default for Qt modules, so new
modules don't need to explicitly specify it in their
.qmake.conf.

Modules can still opt out of the QLinkedList ban by adding
   DEFINES -= QT_NO_LINKED_LIST
to their .qmake.conf.

Change-Id: I34b7ab1c009795649bb7b4f1e7493556eafadd5a
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>