Always report metadata on the path, not symlink target

Metadata are really part of the pathname, not the target file
(as they are stored by pathname, and for many metadata like icon position
etc make not sense using the target data). So, even if nofollow
is not specified we should not follow links for metadata.

Ideally this should be implemented in the metadata extension in gvfs,
but the extension API does not allow this, so we do it in gio.

See https://bugzilla.gnome.org/show_bug.cgi?id=593809