egl/dri2: rework dri2_egl_display::extensions storage

Remove the error prone fixed size array.
While we're here also rename to loader_extensions like in the GLX code.

v2: Rebase. Keep image_loader_extension within the wayland_drm
dri2_loader_extensions list.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
6 files changed