Use list_parents, not get_parents from xdgmime, because the later doesn't

Use list_parents, not get_parents from xdgmime, because the later doesn't

2008-01-29  Alexander Larsson  <alexl@redhat.com>

        * gcontenttype.c:
        (_g_unix_content_type_get_parents):
	Use list_parents, not get_parents from xdgmime, because
	the later doesn't use the cache.

        * xdgmime/xdgmimecache.c:
        (_xdg_mime_cache_list_mime_parents):
	Don't list the same type as parent multiple times.

svn path=/trunk/; revision=6407