A temporary heap array currently stores pids from all streams.  It is
used to make sure there are no duplicated pids. However, this array is
not needed because the pids from past streams are stored in the
MpegTSWriteStream structs.
Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>