This updates the backend part of the output API. This is mostly renaming:
make_current becomes attach_render and swap_buffers becomes commit.
This also fixes the RDP backend to support NULL damage.
The read format is dependent on the output, so we first need to make it
current. This fixes a race condition in wlr-screencopy-v1 where a dmabuf
client would cause EGL_NO_SURFACE to be bound at the time when
screencopy needs to query for the preferred format, causing GL errors.
We were assuming GL_BGRA_EXT was always supported.
We now check that it's supported for rendering. We fail if it isn't because
this format is specified as "always supported" by the Wayland protocol.
We also check if it's supported for reading pixels. A new preferred_read_format
function returns the preferred format that can be used to read pixels. This is
used by the screencopy protocol.
Simon Ser
Timidger
Ilia Bozhinov
Alexander Bakker
Arvin Ignaci