Implement getaddrinfo (somewhat)

Cargo.toml

src/header/netdb/mod.rs

src/header/sys_socket/mod.rs

tests/Makefile

tests/expected/netdb/getaddrinfo.stderr

tests/expected/netdb/getaddrinfo.stdout

tests/expected/netdb/netdb.stderr

tests/expected/netdb/netdb.stdout

tests/netdb/getaddrinfo.c

tests/netdb/netdb.c