binutils/binutils: do not forget to extract elf2flt

In case we're using a custom (aka local) binutils source, we still
need to extract and patch elf2flt.

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"