Git: Allow push after fixup

Direct push after fixup is really useful, especially on gerrit, because
it allows easy fixing and direct pushing commits under HEAD.

Change-Id: I83980e451c9ae86ac1ac0a55170d6d4141f27d49
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitplugin.h

@@ -99,6 +99,7 @@ public:
     void setSettings(const GitSettings &s);
 
     GitClient *gitClient() const;
+    Gerrit::Internal::GerritPlugin *gerritPlugin() const;
 
 public slots:
     void startCommit();