Stabilize tst_qabstractitemview

Attempt to fix

 FAIL! : tst_QAbstractItemView::task200665_itemEntered() Compared values are not the same
    Actual (spy.count()): 0
    Expected (1) : 1
    Loc: [tst_qabstractitemview.cpp(1292)]

which might have been introduced by removing the absolute qWait(200) in favor
of qWaitForWindowExposed() in afe8e368, so trying to compensate with a
QTRY_COMPARE.

Change-Id: Id437acd810b54e005daaf66ffffd4dd586075ab6
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>