cc/gcc: add build frontend

Bizarrely enough, the core gcc are not enough to be able to build a
canadian cross, and a real, full cross compiler is required so that
the canadian cross can be properly built... WTF?!? Sigh...

Add a build-frontend, as was done for the binutils and the complibs.

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

#!/bin/sh

set -e

printf "Running autoconf...\n"

autoconf -Wall --force

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