Remove unnecessary Q_OBJECT from IDocument subclasses

They don't have signals, properties or translatable strings.

Change-Id: Id27df47d1fb8d0530fdf0f5f0d33a2e7b70360af
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -94,7 +94,6 @@ namespace Internal {
 
 class QmakeProjectFile : public Core::IDocument
 {
-    Q_OBJECT
 public:
     QmakeProjectFile(const QString &filePath);