glibc: nios2: Prevent selecting unsupported versions
Versions previous to glibc v2.21 do not support the Nios-II architecture
so disable them.
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Ezequiel García