cc/gcc: add language helper function

Add a function that prepares the language configure option.
It is needed in at least two places, some commonalisation is needed. ;-)

Unfortunately, it is no longer possible to print warnings about experimental
languages any more. Anyway, the experimental status is clearly indicated
in the menuconfig. so it should not be a surprise if the build breaks. :-/

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"