Key frame macrobock and block mode probabilities are constant.
Remove the allocation of tables for each codec instance and use
instead the default const prob tables.
Change-Id: I8361798ac491f9b3889e86925a494c58647c753f
(see Change I9b2ccc88: Makes all mode token tables const)
Further remove runtime table initialization and use
precalculated const data. Data footprint reduced
by 4112 bytes.
Change-Id: Ia3ae9fc19f77316b045cabff01f6e5f0876a86ab
