Relicense granby by RPGillespie6

Received by Github comment:
https://github.com/zeromq/libzmq/pull/2536#issuecomment-528961084

RELICENSE/RPGillespie6.md

+# Permission to Relicense under MPLv2 or any other OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by Bryan Gillespie (RPGillespie6)
+that grants permission to relicense his copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2) or any other
+Open Source Initiative approved license chosen by the current ZeroMQ
+BDFL (Benevolent Dictator for Life).
+
+A portion of the commits made by the Github handle "RPGillespie6", with
+commit author "Bryan Gillespie <rpgillespie6@gmail.com>", are copyright of Bryan Gillespie.
+This document hereby grants the libzmq project team to relicense libzmq,
+including all past, present and future contributions of the author listed
+above.
+
+Bryan Gillespie
+2019/09/06