Add a relicense-file.

RELICENSE/std-any-emplace.md

+# Permission to Relicense under MPLv2 or any other share-alike OSI approved license chosen by the current ZeroMQ BDFL
+
+This is a statement by the Github user "std-any-emplace"
+that grants permission to relicense its copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2) or any other 
+share-alike 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 "std-any-emplace", with
+commit author "std-any-emplace", are copyright of the Github user "std-any-emplace".
+This document hereby grants the libzmq project team to relicense libzmq, 
+including all past, present and future contributions of the author listed above.
+
+"std-any-emplace"
+2020/01/19
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