Fix -Wsuggest-override warnings from Clang 11+

Before this patch, Clang versions greater than 11.0.0 emitted
-Wsuggest-override warnings whenever the Q_OBJECT macro was used.

Excerpt from compiling GammaRay against Qt 6, using Clang 13.0.0:

```
.../qtbase/src/corelib/io/qfile.h:96:5: warning: 'qt_metacall' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
    Q_OBJECT
    ^
.../qt5/qtbase/src/corelib/kernel/qtmetamacros.h:166:17: note: expanded from macro 'Q_OBJECT'
    virtual int qt_metacall(QMetaObject::Call, int, void **); \
                ^
.../qt5/qtbase/src/corelib/io/qfiledevice.h:54:5: note: overridden virtual function is here
    Q_OBJECT
    ^
.../qt5/qtbase/src/corelib/kernel/qtmetamacros.h:166:17: note: expanded from macro 'Q_OBJECT'
    virtual int qt_metacall(QMetaObject::Call, int, void **); \
                ^
```

This was also discussed on the QtCreator mailing list:
  https://www.mail-archive.com/qt-creator@qt-project.org/msg08500.html

Pick-to: 6.2 6.3
Change-Id: I149782472ce8a2e30ed8062ada460c39926f1613
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions