Fix tst_qtracebench benchmark.

Default QDataStream version was changed in Qt5, but the test tried to
load an old dumped file.

Change-Id: I49c06c232ec8a27f33c9da345bae4e03cd0c56fb
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

tests/benchmarks/gui/painting/qtracebench/tst_qtracebench.cpp

@@ -179,6 +179,7 @@ ReplayWidget::ReplayWidget(const QString &filename_)
     }
 
     QDataStream in(&file);
+    in.setVersion(QDataStream::Qt_4_7);
 
     char *data;
     uint size;