[AVR] Add support for XMEGA arch and devices.

[Denis Chertykov]

2011/3/22 Weddington, Eric <Eric.Weddington@atmel.com>:
> Hi All,
>
> Attached is the patch to add support for the AVR XMEGA family of devices. This adds support for new architectures (groupings), device names, and support for new opcodes that are used in this family.
>
> This is the patch that has been used out in the field in several AVR toolchain distributions successfully for a long time.
>
> Ok to commit?

Please, commit.

Denis.