tst_QTimeLine is unstable on Linux

 Testing tst_QTimeLine
FAIL! : tst_QTimeLine::reverse(start at half) 'endValue < firstValue' returned FALSE. ()
Loc: [tst_qtimeline.cpp(441)]
Totals: 25 passed, 1 failed, 0 skipped
QtQA::App::TestRunner: test failed, running again to see if it is flaky...
********* Start testing of tst_QTimeLine *********
Config: Using QtTest library 5.1.0, Qt 5.1.0
PASS : tst_QTimeLine::initTestCase()
PASS : tst_QTimeLine::range()
PASS : tst_QTimeLine::currentTime()
PASS : tst_QTimeLine::duration()
FAIL! : tst_QTimeLine::frameRate() 'slowCount < spy.count()' returned FALSE. ()
Loc: [tst_qtimeline.cpp(219)]
PASS : tst_QTimeLine::value()
PASS : tst_QTimeLine::currentFrame()
PASS : tst_QTimeLine::loopCount()
PASS : tst_QTimeLine::interpolation()
PASS : tst_QTimeLine::reverse(start at end)
PASS : tst_QTimeLine::reverse(start at half)
PASS : tst_QTimeLine::reverse(start at quarter)
PASS : tst_QTimeLine::toggleDirection()
XFAIL : tst_QTimeLine::frameChanged() QTBUG-24796: QTimeLine runs slower than it should
Loc: [tst_qtimeline.cpp(475)]
PASS : tst_QTimeLine::frameChanged()
PASS : tst_QTimeLine::stopped()
PASS : tst_QTimeLine::finished()
PASS : tst_QTimeLine::isRunning()
PASS : tst_QTimeLine::multipleTimeLines()
PASS : tst_QTimeLine::sineCurve()
PASS : tst_QTimeLine::cosineCurve()
PASS : tst_QTimeLine::outOfRange()
PASS : tst_QTimeLine::stateInFinishedSignal()
PASS : tst_QTimeLine::resume()
PASS : tst_QTimeLine::restart()
PASS : tst_QTimeLine::setPaused()
PASS : tst_QTimeLine::cleanupTestCase()
Totals: 25 passed, 1 failed, 0 skipped
********* Finished testing of tst_QTimeLine *********