libc/newlib: update fetch location

The menu system provides an option to allow a user to request newlib
version 2.0.0. newlib-2.0.0, however, is not available at the download
location currently being used. It is, however, available (as are other
supported versions of newlib) at an alternate location.

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Message-Id: <75ab5151c7f5dc9086e3.1362334313@suse64>
Patchwork-Id: 224561

# Options specific to crosstool-NG acting as a backend

config IS_A_BACKEND

    string

    option env="CT_IS_A_BACKEND"

config BACKEND

    bool

    default y if IS_A_BACKEND = "y" || IS_A_BACKEND = "Y"

config BACKEND_ARCH

    string

    option env="CT_BACKEND_ARCH"

config BACKEND_KERNEL

    string

    option env="CT_BACKEND_KERNEL"

config BACKEND_LIBC

    string

    option env="CT_BACKEND_LIBC"