When user use the hls_wrap, there have many problem:
1. some platform refersh the old but usefull segment
2. CDN(Content Delivery Network) Deliver HLS not friendly

The hls_wrap is used to wrap segments for use little space,
now user can use hls_list_size and hls_flags delete_segments
instead it.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Reviewed-by: Carl Eugen Hoyos <ceffmpeg@gmail.com>
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>