Provide socket option definitions

Hi,
I've noticed there's no definition in __header_sys_socket.h for socket options. Is that intentional? I see other definitions (e.g. AF_INET) are already added to the header, but I can't find it anywhere in the WASI spec (so I'm not sure why e.g. AF_INET is defined as 1, even though in linux headers it's 3).
I can also see SO_TYPE being already included, but that's the only option that's available (and is set to 3, which matches Linux headers).

If lack of those definitions is not intentional, I can provide a PR for that; however, I'm not sure what numbers should be assigned to a specific definition - is there any specification already? (as I said, I couldn't find one for AF_INET either).

Many thanks

Start by comparing libc-bottom-half/headers/public/__header_sys_socket.h with libc-top-half/musl/include/sys/socket.h around line 209, then check the WASI specification for socket-option assignments. Resolve whether definitions are intentionally absent and where values such as AF_INET and SO_TYPE come from; done requires an agreed specification or numbering source and a defined scope for the missing options.