[apps] Don't forget to call viewWillAppear

At the moment ViewController::viewWillAppear doesn't do anything, so
there is no real impact. But if we want to use it it needs to be called
from subclasses.

apps/shared/function_list_controller.cpp

@@ -38,6 +38,7 @@ FunctionListController::FunctionListController(Responder * parentResponder, Butt
 /* TableViewDataSource */
 
 void FunctionListController::viewWillAppear() {
+  ExpressionModelListController::viewWillAppear();
   computeTitlesColumnWidth();
 }