Quoting of variables in fsusage.m4 and ls-mntd-fs.m4

[Roland Illig]

Roland Illig wrote:
> The quoting hid one bug that appeared due to one variable being used, 
> which had never been defined before. I think it has been fixed upstream.

It has, and I updated our version of ls-mntd-fs.m4 to the one of 
coreutils. I also documented that in the ChangeLog. Sorry that it took 
so long.

Roland