Update coreboot cross toolchain to gcc 4.6.1

- Tested on Mac OS X 10.7.1
- Tested on Ubuntu 10.04 LTS (Lucid Lynx)
- Tested on Ubuntu 11.10 (Oneiric Ocelot)

Please test on Windows and other Linux distributions

Change-Id: I132c01293fc0cff0cfb84556a93c0b8de8e57230
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/250
Tested-by: build bot (Jenkins)
Reviewed-by: Sven Schnelle <svens@stackframe.org>