patch to fix symlink-related GPFs on Linux

[Magnus Ahltorp]

> Possibly relevant:  I had additionally done the above hanging "ls -CF" when 
> I didn't have a token, so I got 6 permission-denieds and a listing of the 
> directory.  I then obtained a token for ece.cmu.edu and retried the "ls 
> -CF"; it sent/received a number of packets and then everything hung.

What happens when you obtain a token is that arlad invalidates all
nodes in xfs, so that might very well be relevant.

/Magnus
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