buildroot

iproute2: bump to version 4.14.1

Remove uClibc build fix; current uClibc version defines the required
macro.

Remove static link fix; fixed upstream.

Rebase the musl libc-compat.h workaround to adapt to upstream headers
location change.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>