security/softether-devel: Update to v4.31.9727-beta

Summary of changes:

• Add the new function to reserve and each Virtual MAC address and IP address for each user of L2TP/IPsec, SSTP and OpenVPN L3
• Add the "<CA>" field on the auto-generated OpenVPN configuration file
• Add the code to use the optimized OpenSSL's implementation to compute the AEAD_CHACHA20POLY1305 algorithm if available
• Add DisableJsonRpcWebApi switch to hide index.html
• Add DisableIPsecAggressiveMode switch to moderate CVE-2002-1623

Relnotes: https://www.softether.org/5-download/history
Sponsored by: HAW International, Inc.