BC5: Using channels other than 0 and 1 (via rdo_bc_params::m_bc45_channelX) with RDO generates corrupted image

[shacklettbp]

The issue seems to be that the RDO code doesn't account for rdo_bc_params::m_bc45_channel0 or rdo_bc_params::m_bc45_channel1. The workaround is easy: I just permute the channels in my source image, but I wanted to report here in case other people run into this unawares.

Thank you very much for making an open source RDO compressor by the way!

[richgel999]

Thanks! I'll add a note or an assert.