openbsd: correct few structs
openbsd: correct few structs

- addrinfo: addr and canonname are switched (wrong layout)
- addrinfo, Flock, msghdr struct: use proper c_xxx type instead of fixed size. it should help using struct on all architectures supported by openbsd

andrewrk/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,andrewrk/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig