bug#19607: issue with Emacs 24.4.1 but not with 24.3.1 : changed on disk; really edit the buffer

[Jakob Unterwurzacher]

Looks like that's it. I have added printfs so I understand what is 
going on:

   CIFS:

       Emacs should work around this POSIX-conformance bug.
       stat #1: 1422398418.561215369
       stat #2: 1422398418.561215300
       stat #3: 1422398418.561215300


   CIFS + encfs:

       Emacs does not work around this POSIX-conformance bug.
       stat #1: 1422398433.735274107
       stat #2: 1422398433.735274107
       stat #3: 1422398433.735274100


   CIFS + "encfs -o attr_timeout=0":

       Emacs should work around this POSIX-conformance bug.
       stat #1: 1422398527.607547169
       stat #2: 1422398527.607547100
       stat #3: 1422398527.607547100


The kernel caches FUSE stat() values for 1 second by default, this 
defeats emacs' workaround.
Passing "-o attr_timeout=0" to encfs disables that cache.