The speed feature FINAL_PASS_TRELLIS_OPT is meant to disable
optimize_b during the transform search but allow it for the
final encode of blocks. There was a previously existing macro
called DISABLE_TRELLISQ_SEARCH, which does the same thing. This
patch merges the functionality so the macro serves only to enable
the speed feature.

Change-Id: Ieee70f97f817998b7ca275f6e4647cc89a330ad6