buildroot

Prevent C++ + locale + uClibc 0.9.31 + gcc 4.2 to be selected

The problem fixed by 60f945e47a15e10f0e777f69b05492b6f7ba918d is in
fact not limited to the AVR32 architecture, as reported by Will Newton
on the list. The issue is the combination uClibc 0.9.31 with gcc 4.2,
C++ support and locales.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>