core: Copy the factory list before creating devices
core: Copy the factory list before creating devices

We iterate over the copy of the list rather than list itself because
there is high chances of the original list being modified during the
iteration, which is not allowed by libgee.

Tarnyko/rygel,jku/rygel,luisbg/rygel,jku/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Pelagicore/Media-Manager-Rygel-patched,Tarnyko/rygel,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,GNOME/rygel