K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2014-06-22T21:37:27.734430Z
K 7
svn:log
V 328
Don't take filedesc lock in fdunshare().

We can read refcnt safely and only care if it is equal to 1.

If it could suddenly change from 1 to something bigger the code would be
buggy even in the previous form and transitions from > 1 to 1 are equally racy
and harmless (we copy even though there is no need).

MFC after:	1 week

END