Explicitly set tx_type for sub8x8 blocks
Explicitly set tx_type for sub8x8 blocks

Fixes an issue where the tx_type was not set correctly for
sub8x8 inter and intra blocks. In the current syntax, for
sub8x8 blocks, there is still a single tx_type that is
transmitted. Ideally, this should be searched for the best
rd performance, albeit at the expense of encode speed.
For now, we just set it to DCT_DCT. Previously it was left
incorrectly as what was used for the previous non sub8x8
block.

derflr: BDRATE -0.277%

Change-Id: If76ba903bfbfd4d374cf1ac7d1daee50e92f0edd

mbebenita/aom,mwgoldsmith/libvpx,ittiamvpx/libvpx-1,mbebenita/aom,Topopiccione/libvpx,webmproject/libvpx,GrokImageCompression/aom,mbebenita/aom,ShiftMediaProject/libvpx,ittiamvpx/libvpx-1,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,mwgoldsmith/vpx,Topopiccione/libvpx,webmproject/libvpx,GrokImageCompression/aom,webmproject/libvpx,mwgoldsmith/vpx,luctrudeau/aom,luctrudeau/aom,webmproject/libvpx,smarter/aom,mbebenita/aom,ShiftMediaProject/libvpx,mbebenita/aom,GrokImageCompression/aom,smarter/aom,mwgoldsmith/vpx,Topopiccione/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/vpx,webmproject/libvpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,ittiamvpx/libvpx-1,luctrudeau/aom,mwgoldsmith/libvpx,Topopiccione/libvpx,smarter/aom,mbebenita/aom,GrokImageCompression/aom,ittiamvpx/libvpx-1,Topopiccione/libvpx,mbebenita/aom,ShiftMediaProject/libvpx,mbebenita/aom,luctrudeau/aom,smarter/aom,smarter/aom,mwgoldsmith/libvpx,ittiamvpx/libvpx-1,mwgoldsmith/vpx,mbebenita/aom,mwgoldsmith/libvpx,luctrudeau/aom,mwgoldsmith/vpx,webmproject/libvpx,GrokImageCompression/aom,mwgoldsmith/libvpx,ittiamvpx/libvpx-1