Update for avr-binutils to version 2.20

[abusse@…]

I have built a Portfile for avr-binutils for version 2.20 which should solve the problem described here ​http://trac.macports.org/ticket/20839. Furthermore I’ve got rid of all the patches. I assume they did some sort of avr specific tuning in version 1.16 but because none up-to-date build guides for the avr toolchain mention any patching of this kind, I thought they are not necessary anymore.

But there is still one problem I could not fix to my satisfaction. It is mentioned in the Portfile. So maybe someone will have the time to look into it at some point. Until then the utils have to work with the - not so nice - workaround.