set Iounit when allocating auth fids

[GoogleCodeExporter]

if the iounit of the auth fid is not set, Tread messages will get packed with a 
0 read count, resulting in auth always failing on the first read of the auth 
fid.

patch follows.
==============

diff -r 630c71178faf p/clnt/mount.go
--- a/p/clnt/mount.go   Wed May 14 13:19:14 2014 -0600
+++ b/p/clnt/mount.go   Sat Aug 30 06:26:39 2014 +0000
@@ -24,6 +24,7 @@
                return nil, err
        }

+       fid.Iounit = clnt.Msize - p.IOHDRSZ
        fid.User = user
        fid.walked = true
        return fid, nil

Original issue reported on code.google.com by mischief@offblast.org on 30 Aug 2014 at 6:26

[GoogleCodeExporter]

Original comment by lion...@gmail.com on 5 Dec 2014 at 6:10

• Changed state: Fixed