VcsManager: Register IVersionControls with VcsManager

Get some more objects out of the pool.

Change-Id: Id93021b712307c4777dc39b9d15aa18a46318885
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/perforce/perforceplugin.cpp

@@ -183,7 +183,7 @@ bool PerforcePlugin::initialize(const QStringList & /* arguments */, QString *er
     Q_UNUSED(errorMessage)
     Context context(PERFORCE_CONTEXT);
 
-    initializeVcs(new PerforceVersionControl(this), context);
+    initializeVcs<PerforceVersionControl>(context, this);
 
     m_instance = this;