cc/gcc: cleanup the _or_later logic

So far, we've had a version always select appropriate _or_later option,
which in turn would select all previous _or_later options.

Because the dependencies on companion libs were cumulative, that was
working OK. But the upcoming 4.6 will no longer depend on libelf, so
we can't keep the cumulative scheme we've been using so far.

Have each release family select the corresponding dependencies, instead
of relying on selecting previous _or_later.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Blackfin specific configuration file

config ARCH_blackfin

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_DEFAULT_LE

    select ARCH_SUPPORT_ARCH

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    select ARCH_SUPPORT_FPU

     help

      The Blackfin architecture