Define optarg, optind, opterr, and optopt.

That's necessary on Windows, where you're not going to get them defined
by getopt().
Merge branch 'master' of git+ssh://bpf.tcpdump.org/tcpdump/master/git/tcpdump
Rename our getopt.h to getopt_long.h.

That way, if we *do* have getopt_long(), we don't end up including our
getopt.h rather than the system's getopt.h.
Oops, forgot to fix missing/getopt_long.c to include getopt_long.h.
Split the OSPFv3 header and bodies into separate structures.

Some compilers appear to put some padding before the ospf6_un union, so
the OSPFv3 packets aren't dissected correctly.  Pull the members of
that union into separate structures, and find the pointer to the OSPFv6
body by adding the header length to the pointer to the beginning of the
header.
Don't assume the Perl interpreter is in /usr/bin/perl.

It's not necessarily there on all platforms.  Explicitly invoke the
interpreter to run the TESTonce script; that requires that, when you run
"make check", your path includes the directory in which the Perl
interpreter resides.
Just use #! /usr/bin/env perl.

That's a simpler way to deal with the Perl interpreter not being in
/usr/bin.
Sort options and put in notes for unusable option letters.

Sort the options alphabetically, and put in comments for the options
we're *currently* not using, to note that other versions of tcpdump use
them and that we should only use them for the same purposes.