Git: clean forward declaration

Change-Id: Ic8e988d9fa27f9e92fdcfe111220a5c929998afb
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitplugin.h

@@ -39,9 +39,7 @@
 #include <functional>
 
 QT_BEGIN_NAMESPACE
-class QFile;
 class QAction;
-class QFileInfo;
 QT_END_NAMESPACE
 
 namespace Core {
@@ -61,7 +59,6 @@ namespace Internal {
 
 class GitVersionControl;
 class GitClient;
-class GitSubmitEditor;
 class CommitData;
 class StashDialog;
 class BranchDialog;