[Development] Consistently flaky test QTabWidget test

[Thiago Macieira]

8 out of 8 integrations attempted in both qtbase/dev and qtbase/5.11 yesterday 
resulted in

 FAIL!  : tst_QTabWidget::paintEventCount() Compared values are not the same
    Actual   (tab2->count): 2
    Expected (1)          : 1
    Loc: [tst_qtabwidget.cpp(573)]
[on macOS 10.12]

This test *is* flaky because it succeeded in one of the retries, but 
apparently failed the other 16 runs.

Can someone take a look?

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center