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

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