Fix https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5608 :

Fix https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5608 :

getopt() can/should normally be found in unistd.h, so:

- When testing for getopt(), define that we HAVE_GETOPT instead of
  HAVE_GETOPT_H (to avoid confusion).
- Don't attempt to include getopt.h: not all OS's have it (for example,
  Solaris 9 does not).
- (All the places which need getopt already include unistd.h (if we have it).)

If this breaks things on some OS, we might need (a real) HAVE_GETOPT_H check.

svn path=/trunk/; revision=38437