dri: add queryCompatibleRenderOnlyDeviceFd() to __DRI_MESA extension

With this change we are able to query the render node fd of a
render-only device compatible with a given KMS-only device (at the
egl/dri2 level).

It uses pipe_loader_get_compatible_render_capable_device_fd(), which was
added in commit "pipe-loader: add
pipe_loader_get_compatible_render_capable_device_fd()".

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24825>

include/GL/internal/mesa_interface.h

@@ -61,6 +61,8 @@ struct __DRImesaCoreExtensionRec {
 
    /* driver function for finishing initialization inside createNewScreen(). */
    const __DRIconfig **(*initScreen)(struct dri_screen *screen);
+
+   int (*queryCompatibleRenderOnlyDeviceFd)(int kms_only_fd);
 };
 
 #endif /* MESA_INTERFACE_H */