Added a new expt rect-tx to be used in conjunction with ext-tx.
[rect-tx is a temporary config flag and will eventually be
merged into ext-tx once it works correctly with all other
experiments].
Added 4x8 and 8x4 tranforms for use initially with rectangular
sub8x8 y blocks as part of this experiment.
There is about a -0.2% BDRATE improvement on lowres, others pending.
When var-tx is on rectangular transforms are currently not used.
That will be enabled in a subsequent patch.
Change-Id: Iaf3f88ede2740ffe6a0ffb1ef5fc01a16cd0283a
This change has no performance impact. It prepares the proper
function interface for better performance optimization.
Change-Id: I12e2f2deaf7f3adc603de0a74852116468c762f6
