The stdout always becomes line buffered mode.

[DJ Delorie]

> The latest newlib always sets the stdout to the line buffered
> mode against the standard quoted below.
> 
>   ISO/IEC 9899:1999, Second Edition 1999-12-01, p.266
>     As initially opened, the standard error stream is not fully buffered;
>     the standard input and standard output streams are fully buffered if
>     and only if the stream can be determined not to refer to an interective
>     device.

The streams aren't fully buffered, they're line buffered.  I think
this complies with the spec.  I think your patch is correct, but not
because of that standard.  The ChangeLog entry explains it enough on
its own.