[PATCH 2/3 and 3/3] Rygel-0.5.0: don't stumble if XDG magic directories are not here

[Cyrille Chépélov <cyrille chepelov keyconsulting fr>]

Here's the second and third parts. My $HOME has been created all the way back from the GNOME 1.x days, with a couple dist-upgrade and hardware transplants in the last decade, and somehow Rygel didn't like it too much.

The first (2/3) patch creates a shared "please find the directory or find a tolerable substitute", while the second (3/3) uses it wherever appropriate.

    -- Cyrille

		Cyrille CHÉPÉLOV Recherche & Développement 41 rue Emile Duclaux, 92150 Suresnes Tel:    01 41 38 90 40 Fax:    01 41 38 90 41