Re: `message' not outputting the newline "atomically"

[Paul Eggert]

> > However, if that is the route you are suggesting, it is much easier to
> > enable line buffering unconditionally ad place fflush() calls where it
> > matters, than the other way around.
> You are suggesting fflush after every character written?

I think he was suggesting enabling line buffering (_IOLBF) unconditionally, and 
also placing fflush where we want the output right away even on MS-Windows. The 
fflush would be needed only for MS-Windows, because MS-Windows is the only Emacs 
platform where using _IOLBF does not work (MS-Windows silently treats requests 
to use line buffering as if they requested full buffering, which is not what we 
want for stderr).

If this is the compromise needed to fix this problem then let's do it. _IOLBF is 
a simple and effective solution to this problem on GNU and other POSIXish 
platforms, and we shouldn't let MS-Windows's lack of support for a useful 
feature prevent Emacs from using the feature on non-MS-Windows platforms.