[REG 3.6.1->4.x] Auto-generated includes from UIC are not parsed properly

Included auto-generated ui files aren't parsed properly.

#include "ui_MainWindow.h"

This causes that all clases which are only included in auto-generated ui file aren't available for completer and highlighter.

In UiFile.png attachment you can see that no class is highlighted (which is properly included and known to the compiler).

E.g. If I manually change the ui file name or ui file location (for test purpose only) then QtCreator parses it properly.

This bug exists on both: CMake and QMake projects.

Steps to reproduce:

• unpack "UiCompletion.zip",
• open CMake or QMake project,
• compile,
• go to "MainWindow.hpp" and open auto-generated "ui_MainWindow.h" file,
• notice, that it is not parsed properly,
• try to use completer on e.g. QToolBar which is included only in the ui file - nothing happens.

This bug can be related to QTCREATORBUG-16578.