doc: Document another portability problem of 'od'.

* doc/autoconf.texi (Limitations of Usual Tools): Document that decimal output
is not portable.

doc/autoconf.texi

@@ -19773,14 +19773,33 @@ perfectly portable among Posix hosts.
 @c ---------------
 @prindex @command{od}
 
-In Mac OS X 10.3, @command{od} does not support the
+In MacOS X versions prior to 10.4.3, @command{od} does not support the
 standard Posix options @option{-A}, @option{-j}, @option{-N}, or
 @option{-t}, or the XSI option, @option{-s}.  The only
 supported Posix option is @option{-v}, and the only supported
 XSI options are those in @option{-bcdox}.  The BSD
 @command{hexdump} program can be used instead.
 
-This problem no longer exists in Mac OS X 10.4.3.
+In some versions of some operating systems derived from Solaris 11,
+@command{od} prints decimal byte values padded with zeroes rather than
+with spaces:
+
+@smallexample
+$ @kbd{printf '#!' | od -A n -t d1 -N 2}
+         035 033
+@end smallexample
+
+@noindent
+instead of
+
+@smallexample
+$ @kbd{printf '#!' | od -A n -t d1 -N 2}
+          35  33
+@end smallexample
+
+We have observed this on both OpenIndiana and OmniOS;
+Illumos may also be affected.
+As a workaround, you can use octal output (option @code{-t o1}).
 
 
 @item @command{rm}