The original implementation only allocates one segmentation map and this
works fine for serial decode. But for frame parallel decode, each thread
need to have its own segmentation map and the last frame segmentation map
should be provided from last frame decoding thread.
After finishing decoding a frame, thread need to serve the old segmentation
map that associate with the previous decoded frame. The thread also need to
use another segmentation map for decoding the current frame.
Change-Id: I442ddff36b5de9cb8a7eb59e225744c78f4492d8
7eca086707