Re: GPL version of ax_cflags_warn_all.m4

[Rhys Ulerich]

> The macro files that seem to be affected (i.e. originally written by
> Guido, but since modified) are:
>
> ...
>
> and the authors affected are: Marten Svantesson, Gerald Point, Rhys
> Ulerich, Sven Verdoolaege and Alan Jenkins.
>
> If any of them happens to read this and doesn't mind the license
> requirement being bumped to GPLv3+, then please say so!

Feel free to autobump the GPL versions on anything to which I've contributed.

- Rhys