[apps/regression/graph] Fix roundCursorView drawing glitch

Scenario:
f(x)=cos(x)
CalculateZeroes -> drawing glitch
Right, Back -> drawing glitch

apps/graph/graph/graph_controller.cpp

@@ -31,6 +31,9 @@ I18n::Message GraphController::emptyMessage() {
 
 void GraphController::viewWillAppear() {
   m_view.drawTangent(false);
+#ifdef GRAPH_CURSOR_SPEEDUP
+  m_cursorView.resetMemoization();
+#endif
   m_view.setCursorView(&m_cursorView);
   FunctionGraphController::viewWillAppear();
   selectFunctionWithCursor(indexFunctionSelectedByCursor());

apps/regression/graph_controller.cpp

@@ -45,6 +45,9 @@ I18n::Message GraphController::emptyMessage() {
 }
 
 void GraphController::viewWillAppear() {
+#ifdef GRAPH_CURSOR_SPEEDUP
+  m_roundCursorView.resetMemoization();
+#endif
   /* At this point, some series might have been removed from the model. We need
    * to reinitialize the selected series index if the current selection is
    * either null (right after construction) or refering a removed series. */