overlay: use xattrs perms with network FSs
overlay: use xattrs perms with network FSs

when running in a user namespace on a network file system,
automatically switch on the permission xattrs feature so that users
won't have to tweak their storage.conf file with difficult to guess
options.

The list of remote file systems was taken from coreutils stat:

https://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/stat.c;h=0c34501e34410b9096edf377654b9ff27fe9fa24;hb=HEAD#l260

Signed-off-by: Giuseppe Scrivano <20002b7b24c75512093a71a58285826d5c504fca@redhat.com>

containers/storage,containers/storage,containers/storage