Ticket 47699: Propagate plugin precedence to all registered function types
    
    Bug Description:
    	A plugin can define its nsslapd-pluginprecedence (config), that is number that order the
    	plugins in the plugin list.
    	If a plugin register an other plugin (slapi_register_plugin), this number is not
    	preserved in the new plugin and it gets a default plugin precedence value.
    
    Fix Description:
    	When registering a plugin (slapi_register_plugin) a plugin identity is provided that
    	contains the original plugin configuration (with its precedence).
    	The fix consist to set (in slapi_register_plugin_ext ) the precedence to the
    	value store in the plugin identity. It is done in slapi_register_plugin_ext
    	because referencial integrity calls directly slapi_register_plugin_ext.
    
    https://fedorahosted.org/389/ticket/47699
    
    Reviewed by: Rich Megginson / Mark Reynolds
    
    Platforms tested: F17
    
    Flag Day: no
    
    Doc impact: no