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>

 reporter_name="Yann E. MORIN"

 reporter_url="http://ymorin.is-a-geek.org/projects/crosstool"

 reporter_comment="Experimental toolchain for ARM cortex-m3 in Thumb-only, noMMU, and newlib."