Use getopt_long() for the first pass through the argument list.

That way:

	1) we don't have to worry about the system getopt() and our
	   getopt_long(), on platforms that have getopt() but not
	   getopt_long() (Solaris prior to Solaris 10, HP-UX, AIX), not
	   working well together;

	2) if necessary, we can handle long options in the first pass.

Switch to using getopt_long() for the *second* pass for the GTK+ version
of Wireshark.

Use the documented mechanism for resetting the argument parser for the
glibc version of getopt_long(); use the mostly-undocumented-but-at-least-
they-documented-optreset mechanism for the *BSD version.

(We should look into doing only one pass, saving away arguments that
can't fully be processed in the first pass for further processing after
initializing libwireshark.)

Change-Id: Ide5069f1c7c66a5d04acc712551eb201080ce02f
Reviewed-on: https://code.wireshark.org/review/6063
Reviewed-by: Guy Harris <guy@alum.mit.edu>