Embed the rust idct functions. (#613)
Embed the rust idct functions. (#613)

* Call av1_idct4() from inside av1_idct8().

* Call av1_idct8() from inside av1_idct16().

* Use 2 multiply rotation by PI/4.

Adds the full_btr_sqrt2() function that computes a rotation by PI/4
 using 2 multiplies instead of 4.

xiph/rav1e,xiph/rav1e