buildroot

zeromq: bump to version 4.1.3

Add upstream patch to fix build failure of zeromq with latest
libsodium, since sodium_init() has a retval and is now declared to warn
on unused result, with zeromq treating warnings as errors.

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