egl: add support for EGL_EXT_device_drm_render_node
This new EGL extension has been introduced in 1.
When we have a DRM device and a render node, we can advertise the extension and return the render node name for the EGL_DRM_RENDER_NODE_FILE_EXT query.
For the special software EGL device, we can advertise the extension and return NULL for the EGL_DRM_RENDER_NODE_FILE_EXT query, because we can guarantee that llvmpipe will never use a render node for rendering operations.
However, llvmpipe might be using a primary node when used with the GBM platform. So we can't advertise EXT_device_drm in this case.
When we have a DRM device but no render node, that means we're on a split render/display SoC. We should return the render node used by the renderonly driver, however Mesa needs more plumbing to allow this, so let's just disable the extension for now.
Signed-off-by: Simon Ser contact@emersion.fr