mesa: force rendertarget usage on required-renderable formats
What does this MR do and why?
mesa: force rendertarget usage on required-renderable formats
the existing guesswork during format selection for teximage is
accurate most of the time, but it's not accurate all of the time.
GL/ES each have a set of sized formats that are required to be
color renderable, and so any time one of these is allocated as a
texture, it MUST have the rendertarget usage bit attached so that
it can later be bound as a framebuffer attachment
an alternative might be to relax this and then try to do migration
to a different format/buffer later if necessary, but that's hard and
probably not actually as useful
cc: mesa-stable