Revert "Added HELP_MEDIA_NODUP and YELP_INIT_HELP"

This reverts commit 2e63c1ae0f1bad71c6d7b9bf328f919e6372e719.
Going to do an option to YELP_HELP_INIT instead.
yelp.m4: Added no-lc-media-links option for YELP_HELP_INIT

This replaces the HELP_MEDIA_NODUPS variable I'd previously
introduced with a global parameter. It's a bit less flexible,
but much less ugly.