* When wedge and compound-segment are disabled, we don't use
  compound_type_cdf, but it still gets copied around, averaged, etc.
  It's slightly nicer to avoid that when it isn't necessary.

* Fix an anomaly with cb4x4: We had (schematically)
  'if (bsize < 8X8 && CB4X4)', which is backwards when compared to
  other similar conditions elsewhere in the code.
  Change this to 'if (bsize < 8X8 && !CB4X4)" to match other code.

Change-Id: If802cf4f305c30cd642d0d5dd6610b547b52a027