Add a new Wiretap encapsulation type for Cisco HDLC. Map the NetBSD

Add a new Wiretap encapsulation type for Cisco HDLC.  Map the NetBSD
DLT_HDLC to it.

Make a separate dissector for Cisco HDLC, and add a dissector for Cisco
SLARP.  Have the PPP dissector call the Cisco HDLC dissector if the
address field is the Cisco HDLC unicast or multicast address.  Use the
Cisco HDLC dissector for the Cisco HDLC Wiretap encapsulation type.

Add a new dissector table "chdlctype", for Cisco HDLC packet types
(they're *almost* the same as Ethernet types, but 0x8035 is SLARP, not
Reverse ARP, and 0x2000 is the Cisco Discovery protocol, for example),
replacing "fr.chdlc".

Have a "chdlctype()" routine, similar to "ethertype()", used both by the
Cisco HDLC and Frame Relay dissectors.  Have a "chdlc_vals[]"
"value_string" table for Cisco HDLC types and protocol names.  Split the
packet type field in the Frame Relay dissector into separate SNAP and
Cisco HDLC fields, and give them the Ethernet type and Cisco HDLC type
"value_string" tables, respectively.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@3133 f5534014-38df-0310-8fa8-9805f1628bb7