scripts: update mk-release to cope with the new autoconf framework

Now that ./configure is generated by autoconf, it must be generated
before the release tarball is made. So, we can not simply use hg's
archive, we must post-process it.

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"