Those are pretty old. These are old too: http://ww1.microchip.com/downloads/archive/avr32-gnu-toolchain-3.4.0.332-source.zip
There are even old sources here: https://www.microchip.com/en-us/development-tools-tools-and-software/avr-and-sam-downloads-archive There slightly newer gcc-avr32 RPMs available for various Linux distributions (like *gcc*-*avr32*-linux-gnu-4.8.5-16.el7.1.x86_64.rpm for CentOS 7). Maybe a source RPM could be modified?
