This is ported from packetdrill 2.0.

This is from packetdrill 2.0 with the addition of support for
--define=PROTO=132

You can use -Dproto=IPPROTO_SCTP or --define proto=IPPROTO_SCTP
and run the script
```
 0.0 socket(..., SOCK_STREAM, proto) = 3
+0.0 close (3)
```
to control the protocol being used from the command line.

This avoids conflics with definitions on Solaris 10.4.

Remove the inclusion of netinet/sctp.h after enabling SCTP support
in platfroms.h.

The Solaris Studio compiler uses different flags...

It seems that -pthread is not really needed...

Add MacOS support