o wrapped an ifdef() around AM_PATH_MOVTAR in configure.in
(so that if you don't have movtar and don't want movtar,
you don't need it.)
o detect if __progname is defined on system.
mjpeg_logging.c/h:
o log output now includes an identifier, defaulting to the name of the
executable (or "???" if __progname doesn't exist).
o added function to set the identifier (if program wants to explicitly).
