buildroot

iproute2: bump to version 4.5.0

Drop 0003-iproute2-fix-building-with-musl.patch since it's upstream.
Add gentoo patch to allow for non-iptables builds.
Add new musl build fix.
Tweak 0001-Avoid-in6_addr-redefinition.patch since the first chunk is no
longer required.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>