Some SO_* constants like SO_BROADCAST and SO_LINGER aren't defined

[nickrum]

While WASI does not (yet) support UDP broadcast or TCP linger, it would still be useful if these constants were defined, similar to how all the IP_*, IPV6_* and TCP_* constants are defined, even though WASI doesn't support all the related functionality.

Specifically, this came up while adding socket support to the Rust wasm32-wasip2 target. Since the part of the implementation that is common to all targets makes use of these constants, adding them to wasi-libc would allow this to be done without introducing conditional compilation to the common implementation.

[abrown]

This makes sense; are you interested in adding these? (cc: @badeend, @dicej)

[nickrum]

Sure, I'll give it a shot 👍