Bug 218350

Environment:
 - KDE with Oxygen theme
 - kernelshark-v2.3.0 (Qt6 build)

Note: I do not have any issue with kernelshark-v2.2.1. These bugs are triggered by the
migration to Qt6.

Here my analysis:

In KsGLWidget::_defaultPlots(), _model.reset() is called, which will call endResetModel().
This will trigger (synchronously) a call to KsGLWidget::resizeGL():
 - At this point _model.histo() is empty, since previously reset, so both min and max
   histo fields are 0.
 - A call to ksmodel_set_bining() will update max value to an invalid value (too small)
 - _model.fill(_data) is called "KsGraphModel::fill()", which call ksmodel_fill ->
   ksmodel_set_upper_edge
 - The kshark_find_entry_by_time() is going to return BSEARCH_ALL_GREATER (since max is
   smaller than all timestamp) => ASSERT

There is another problem:
 - From KsGLWidget::_defaultPlots(), _model.reset() is called, which will call 
   endResetModel()
 - This will trigger (synchronously) a call to KsGLWidget::resizeGL()
 - Which is going to execute _model.fill(), which is going to call endResetModel()
 - This will trigger (synchronously) a call to KsGLWidget::resizeGL()
 - ... => Stackoverflow

I tried to fix it by adding to resizeGL():

    if (_model.histo()->min == 0 && _model.histo()->max == 0)
        return;

    if (_model.histo()->n_bins == nBins)
        return;

With this "fix" the application can open a trace-cmd file without crashing.
But there is still a lot of issue