Add CONFIG_DAALA_DCT64 experiment.

This experiment replaces the 64-point Type-II DCT and related
scaling vp9 transforms with the 64-point orthonormal
Daala transforms.

subset-1:

    monty-square-baseline-s1-F2@2017-07-28T03:35:45.962Z ->
      monty-square-dct64-s1-F2@2017-07-29T04:50:58.412Z

       PSNR | PSNR Cb | PSNR Cr | PSNR HVS |    SSIM | MS SSIM | CIEDE 2000
    -0.1930 | -0.2037 | -0.0643 |  -0.1917 | -0.2331 | -0.3510 |    -0.1810

objective-1-fast:

    monty-square-baseline-o1f-F2@2017-07-28T03:35:35.533Z ->
      monty-square-dct64-o1f-F2@2017-07-29T04:50:28.542Z

       PSNR | PSNR Cb | PSNR Cr | PSNR HVS |    SSIM | MS SSIM | CIEDE 2000
    -0.2557 | -0.1743 | -0.4900 |  -0.3028 | -0.4147 | -0.5764 |    -0.2864

Change-Id: I1f944df29e44d2e350c42555af274f2d75a62a92
diff --git a/av1/common/daala_tx.h b/av1/common/daala_tx.h
index b0f24a1..cef35c9 100644
--- a/av1/common/daala_tx.h
+++ b/av1/common/daala_tx.h
@@ -15,5 +15,8 @@
 void od_bin_idst16(od_coeff *x, int xstride, const od_coeff y[16]);
 void od_bin_fdct32(od_coeff y[32], const od_coeff *x, int xstride);
 void od_bin_idct32(od_coeff *x, int xstride, const od_coeff y[32]);
-
+#if CONFIG_TX64X64
+void od_bin_fdct64(od_coeff y[64], const od_coeff *x, int xstride);
+void od_bin_idct64(od_coeff *x, int xstride, const od_coeff y[64]);
+#endif
 #endif