Previously, glocalfile.c would not set file system metadata for
the free/used key for file systems which reported 0 free space. This is
because some file systems don’t set that metadata when you call
statfs(), so we can’t reliably report it. However, some do, and they
can legitimately set f_bavail and f_bfree to 0 if the file system is
full.

In order to avoid that, always set the file system metadata unless the
file system is FUSE or ncpfs.

This is a partial revert of commit 0b9f24c1

: instead of the changes
made in that commit, I think we should maintain a blacklist of file
systems which are known to not correctly report free space.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

GNOME/glib#328