M3UA tests provided by wireshark
http://wiki.wireshark.org/SampleCaptures#Sigtran_Protocol_Family
But RFC4666 tells that parameter 0x0002 aren't carried by M3UA, so
it's OK that tcpdump doesn't know about this identifier.
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The change to sctp_print() does three things:
* makes detection of ForCES consider PPID, not just port number
* verifies chunk length of all SCTP_DATA chunks, not just of ForCES
* adds PPID-specific dispatching with a particular case of M3UA