scripts: fix download from sourceforge

It seems sourceforge changed yet again the way to download files.
This time, no longer use their 'mesh' thingy, and hard-code the
server to use in the URL... Sigh... :-(

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

#!/bin/sh

set -e

printf "Running autoconf...\n"

autoconf -Wall --force

printf "Done. You may now run:\n    ./configure\n"