[PATCH] Fix usage of to_string() for pretty-printers with children

[Eli Zaretskii]

> From: Peter Linss <peter@elemental.software>
> Date: Thu, 25 May 2017 10:51:26 -0700
> Cc: gdb-patches@sourceware.org
> 
> > Please add back the comma removed here.
> > 
> > The documentation part is approved with this gotcha fixed.
> > 
> > Thanks.
> 
> Revised patch with comma restored (not sure if you want a new email thread for small patch revisions like this):

Thanks, this is OK.  For the future, when I say "approved with that
fixed", there's no need to post the corrected patch, just be sure to
correct it before pushing.