libc/uClibc: do not systematically use pre-generated locale data

It seems that using pre-generated locale data can be more problematic
than usefull in some circumstances.

Offer a config knob to enable/disable use of the pregen locale data.
Also, do not extract pregen locales data ourselves, it's broken.

# m68k specific configuration file

# depends on EXPERIMENTAL

config ARCH_m68k

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_DEFAULT_BE

    select ARCH_SUPPORT_CPU

     help

      The m68k architecture