Moved vp9_accumulate_frame_counts to vp9_thread_common.c to eliminate the duplicate code. Change-Id: I9cf506d729603c8bf1494b4c86a3b7d47af1917a
Renames the files to allow more common thread code to be moved to vp9/common. Change-Id: I7386e64e221086e3cdc087e79812f993c423413b