Remove lots of $Header's and a few $Id's that all belong to the former
CVS repository of tcpdump itself. These keywords have been frozen since
the migration to git in late 2008.
into a new gmpls.c file; have gmpls.h contain only external declarations
of those structures. That removes compiler warnings about static
structures being defined but not used, and also lets more than one file
share structures used in both of those files, rather than having private
definitions of them.
