buildroot

glibc: drop version 2.22

We don't want a dozen glibc versions and there's no particular reason to
keep this old version around so drop it.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
[Thomas: add entry to Config.in.legacy.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>