argp: modified behaviour for empty group header

[Alex Regueiro]

Oops, sorry. I didn't see that bit. Or perhaps I was reading the wrong notes even...

Do you want me now to look up the guidelines and resend, or are you content with the existing patch and explanation of its purpose?

> On 8 Jan 2015, at 00:25, Roland McGrath <roland@hack.frob.com> wrote:
> 
> You sent the patch in an attachment and with no ChangeLog fragment outside
> the attachment, so I didn't even look at it.