Make GStreamer aware of external dependencies which affect the feature set of this plugin (ie.
the elements or typefinders associated with it).
GStreamer will re-inspect plugins with external dependencies whenever any of the external dependencies change. This is useful for plugins which wrap other plugin systems, e.g. a plugin which wraps a plugin-based visualisation library and makes visualisations available as GStreamer elements, or a codec loader which exposes elements and/or caps dependent on what external codec libraries are currently installed.
optional flags, or NONE