Avoid UAF after deregister_dissector

Avoid UAF after deregister_dissector

When deregister_dissector is called by Lua, the protocol was not
property removed from the dependent dissectors list. Fix this and also
duplicate the memory for keys and values since these strings might be
dynamically allocated.

Fixes a use-after-free after reloading Lua dissectors that use
DissectorTable:add() and opening a new/closing an existing capture file.

Change-Id: If2ae02f155e7ab8fc653c08003755897471f9be0
Reviewed-on: https://code.wireshark.org/review/14735
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>