Unlike Linux, Solaris, and Illumos (and probably others), the 2 BSDs that still
support SCTP didn't put SCTP into its own library, they put it into libc.
They, unlike Linux, don't set SOL_SCTP for us. The official method appears to
be calling getprotobyname("sctp") & endprotoent(), with getprotobyname()
returning a struct that has a p_proto entry. This all reads from
/etc/protocols. However, SCTP is assigned 132 by IANA, so it's 132 everywhere,
so I just set SOL_SCTP to 132 if it's not already set.
This only supports two addresses as the intended use is 1 IPv4 and 1 IPv6
address on a single-homed host, and the only supported configuration of
outgoing connections to other servers is to bind a single IPv4 or IPv6
address.
libmbedtls depends on libmbedx509 and libmbedcrypto
libmbedx509 depends on libmbedcrypto
They have to be specified in the correct order for the GNU linker to work.
