new Portfile for version bump of mutt-devel

[Olaf Foellinger]

Hi,

I've added bug https://svn.macosforge.org/projects/macports/ticket/11876
to trac together with a diff file for the port file which bumps
mutt-devel to current version 1.5.15. 

I would also agree to take over the maintainership which means I accept
patches and add them to the portfile rather than updating all the
variants mysel.

Please check the bug and commit the file to the repository.

Gruss Olaf