Add relicense grant by Laszlo Boszormenyi (GCS)

RELICENSE/gcsideal.md

+# Permission to Relicense under MPLv2
+
+This is a statement by Laszlo Boszormenyi (GCS) that grants permission to
+relicense its copyrights in the libzmq C++ library (ZeroMQ) under the
+Mozilla Public License v2 (MPLv2).
+
+A portion of the commits made by the Github handle "gcsideal", with
+commit author "Laszlo Boszormenyi (GCS) <gcs@debian.org>", are copyright of
+Laszlo Boszormenyi (GCS) .
+This document hereby grants the libzmq project team to relicense libzmq,
+including all past, present and future contributions of the author
+listed above.
+
+Laszlo Boszormenyi (GCS)
+2020/02/13