pan/lower_blend: bug fixes for gles3.1
Cc @bbrezillon the remaining draw_buffers_indexed fails go away when PAN_MESA_DEBUG=noafbc is passed, so punting the remaining bug to you.
Some of the changes here are just prepping for !10601 (merged)
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
Cc @bbrezillon the remaining draw_buffers_indexed fails go away when PAN_MESA_DEBUG=noafbc is passed, so punting the remaining bug to you.
Some of the changes here are just prepping for !10601 (merged)