Fix build with LibreSSL
Found by Heiko Becker:
LibreSSL unfortunately defines "OPENSSL_VERSION_NUMBER 0x20000000L"
but doesn't support the OpenSSL 1.1 API.
(This is a slightly reworked version of pull request #35.)
diff --git a/THANKS b/THANKS
index 4c70f2c..5bda575 100644
--- a/THANKS
+++ b/THANKS
@@ -27,6 +27,7 @@
François Simon <AT.GFI.Francois.SIMON@sesam-vitale.fr>
Frederik Ramm <frederik@remote.org>
Hanno Böck <hanno@hboeck.de>
+Heiko Becker
Heiko Hund <heiko@ist.eigentlich.net>
Info-ZIP group
Jan Weiß <jan@geheimwerk.de>
