Add support for SCTP to getaddrinfo(3).
Now, getaddrinfo(3) returns two SOCK_STREAMs, IPPROTO_TCP and
IPPROTO_SCTP. It confuses some programs. If getaddrinfo(3) returns
IPPROTO_SCTP when SOCK_STREAM is specified by hints.ai_socktype, at
least Apache doesn't work. So, I made getaddrinfo(3) to return
IPPROTO_SCTP with SOCK_STREAM only when IPPROTO_SCTP is specified
explicitly by hints.ai_protocol.

PR: bin/128167
Submitted by: Bruce Cran <bruceatcran.org.uk> (partly)
MFC after: 2 week