libstagefright: fix the duration "00:00" for some httplive link

if the playlist does not end by '\n', player can not show
the correction duration

Change-Id: I6dd9abfce32a1ef7b7d6ed157c966fce3c190389
Author: Yi Wang <yi.a.wang@intel.com>
Signed-off-by: Yi Wang <yi.a.wang@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 48555