toolchain/external: hide versions too old for the current arch

Hide the toolchains if the arch requires a gcc version more recent
than the one they provide.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
11 files changed