buildroot

iproute2: fix build with musl

This commit adds two patches to the iproute2 package that are
necessary to build it against the musl C library. Both patches have
been submitted upstream.

Fixes:

  http://autobuild.buildroot.org/results/5d3/5d3f8c2242e9a89bb545166fc7d70429d2cddd42/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>