Git: Minor cleanup

* Remove unused includes
* Remove QObject qualification
* Use a raw pointer for widget instead of QPointer. It is owned by GitGrep.

Change-Id: I4e2c9878289ed3491bfd7b0565a683bc01e485f3
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/git/gitgrep.h

@@ -30,9 +30,6 @@
 
 #include <utils/fileutils.h>
 
-#include <QPointer>
-#include <QStringListModel>
-
 QT_FORWARD_DECLARE_CLASS(QCheckBox)
 
 namespace Git {
@@ -56,7 +53,7 @@ public:
             const TextEditor::FileFindParameters &parameters) override;
 
 private:
-    QPointer<QCheckBox> m_widget;
+    QCheckBox *m_widget;
 };
 
 } // namespace Internal