Don't assume that, if you've already seen the packet, you can use the

Don't assume that, if you've already seen the packet, you can use the
global variables to determine if packets were dropped, because you can't
- packets can be visited in any order.  Instead, attach to packets
preceded by dropped packets protocol data, as a flag that packets were
dropped.

Re-initialize the global variables when a capture is opened.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@8062 f5534014-38df-0310-8fa8-9805f1628bb7