binutils: add frontends for building to run on the build machine

In canadian-cross, we need binutils running on the build machine to be
able to build the target C library.

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"