v5.16.3

This is another minor patch release fixing two edge-cases:

1. FTL refused to start on systems with IPv6 disabled at the kernel level.
2. FTL crashed during shutdown on musl libc-based systems.

What's Changed

• Don't enforce API sockets by @DL6ER in #1408
• Fix storing of API thread IDs by @DL6ER in #1410

Full Changelog: v5.16.2...v5.16.3