libmediaplayerservice:delay codec EOS or error message during NuPlayer flushing decoder.

During NuPlayer flush decoder, codec reached EOS or error, and message it to NuPlayer.
If NuPlayerRender has already flushed its video and audio queue, and NuPlayer
still push EOS entry to NuPlayerRender queue, then crash happend because
queue is not empty when finish flush checking queue.

Change-Id: I9079ce282f91d149b4b773b533cf248b833e6e14
Author: Yi Wang <yi.a.wang@intel.com>
Signed-off-by: Yi Wang <yi.a.wang@intel.com>
Signed-off-by: Dan Liang <dan.liang@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: 48710 43878