bug#7574: [PATCH]: echo, printf, stat: Allow only up to 8 bit octal input for backslash-escaped chars

[Ondrej Vasik]

As the same bash request for change in builtin echo and printf
(http://lists.gnu.org/archive/html/bug-bash/2010-12/msg00030.html and
https://www.opengroup.org/sophocles/show_mail.tpl?CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=15087
 ) was rejected, I think we should do the same here to keep echo and printf 
implementations as close as possible.

Anyway, it would be better to be consistent in all utilities -e.g.
tr.c:502 now behaves the way proposed in the patch in this bugzilla -
and at least document that the ninth bit is ignored in the address@hidden
section of info documentation.