arch/avr32: Fix download of header files

This patch fixes the download of the avr32 headers in crosstool-ng by
fetching them directly from Atmel's web site instead of the now-broken URL
given by the original author of the avr32-header-fetching modification,
who fetched them from a copy on his own, now-defunct server.

It also adds the necessary logic to extract from a zip file, as that is
how the headers are packaged.

To configure it for avr32 after launching ct-ng menuconfig in an empty
directory:

Paths and misc options ->
Shell to use as CONFIG_SHELL = sh
Target options ->
Target Architecture = avr32
Toolchain options ->
Tuple's alias = avr32
Binary utilities ->
binutils version = 2.18a
C compiler
gcc version = 4.2.2
C-library
newlib version = 1.17.0
Enable IOs on long long = yes
Enable IOs on floats and doubles = yes
Disable the syscalls supplied with newlib = yes

CONFIG_SHELL is necessary to get round the "fragment: command not
found" bug when binutils-2.18 is configured using bash.

Prepared against crosstool-ng mercurial trunk on 31 March 2012.

Signed-off-by: Martin Guy <martinwguy@gmail.com>
[yann.morin.1998@free.fr: update bundles sample accordingly]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <CAL4-wQrg_NQ7jm-NCADqeyQr9twyhtx42OUGNThP6gWeqZc=kw@mail.gmail.com>
Patchwork-Id: 232612

 This is a somewhat ordered TODO list:

 Recurring tasks:

 - update versions for every tools...

 - update and/or upgrade all samples

 Non-recurring tasks:

 - update newlib (for enhanced bare metal)

   - confirm existing implementation on targets other than AVR32

   - try to make it generic, will help for uClibc++

 - multilib

 - Cygwin target (needs newlib)

   - so we can build toolchains that generate code for Windows/Cygwin

 - Cygwin host

   - so we can build toolchains that run natively under Windows/Cygwin

 - mingw32 target

   - so we can build toolchains that generate code for Windows/Win32

 - mingw32 host

   - so we can build toolchains that run natively under Windows/Win32

     (without requiring Cygwin)

 - uClibc++

   - see newlib, above

 - uClinux

   - check whether we can use newlib under uClinux (?)