Make sure a display name is set for targets

* Make sure we have a display name set for targets when restoring
   from Qt creator 1.3.1 .user files.

src/plugins/qt4projectmanager/qt4target.cpp

@@ -406,6 +406,7 @@ bool Qt4Target::fromMap(const QVariantMap &map)
 {
     bool success = Target::fromMap(map);
     setIcon(iconForId(id()));
+    setDefaultDisplayName(displayNameForId(id()));
     return success;
 }