toolchain: mark uClibc 0.9.31 + locale + C++ as broken

toolchain: mark uClibc 0.9.31 + locale + C++ as broken

It fails to build with:

ctype_members.cc: In constructor 'std::ctype_byname<_CharT>::ctype_byname(const char*, size_t) [with _CharT = char]':
ctype_members.cc:59: error: invalid use of incomplete type 'struct __uclibc_locale_struct'
/home/test/avr32-br/usr/avr32-unknown-linux-uclibc/sys-include/bits/uClibc_locale.h:85: error: forward declaration of 'struct __uclibc_locale_struct'
ctype_members.cc:60: error: invalid use of incomplete type 'struct __uclibc_locale_struct'
/home/test/avr32-br/usr/avr32-unknown-linux-uclibc/sys-include/bits/uClibc_locale.h:85: error: forward declaration of 'struct __uclibc_locale_struct'
ctype_members.cc:61: error: invalid use of incomplete type 'struct __uclibc_locale_struct'
/home/test/avr32-br/usr/avr32-unknown-linux-uclibc/sys-include/bits/uClibc_locale.h:85: error: forward declaration of 'struct __uclibc_locale_struct'
make[5]: *** [ctype_members.lo] Error 1

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