Fix a mismatch in multi-threaded decoder
Fix a mismatch in multi-threaded decoder

The decoder result didn't match while using t=1 or using t=2.
This patch fixed the bug.

Change-Id: I8028d14c6dc5761d7033453affc6ceb0b3e81c89

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom