net/libzmq4: Update to 4.3.4, Fix security issues

• Patches removed were incorporated upstream.

Changelog: https://github.com/zeromq/libzmq/releases/tag/v4.3.2

https://github.com/zeromq/libzmq/releases/tag/v4.3.3
https://github.com/zeromq/libzmq/releases/tag/v4.3.4

PR: 255102
Approved by: koobs (maintainer, implicit)
MFH: 2021Q2
Security: 21ec4428-bdaa-11eb-a04e-641c67a117d8
Security: 6954a2b0-bda8-11eb-a04e-641c67a117d8

Co-authored-by: Danilo G. Baio <dbaio@FreeBSD.org>