xwayland: search for a render node to use

wl_drm's protocol “device” event provides the path to the drm device, which may not be a render node, thus causing Xwayland to fall back to drm authentication which may fail if the user has switched to another VT while Xwayland is starting.

Search for a render node corresponding to the given DRM device and try to use it instead, as render nodes do not need authentication and Xwayland can make use of them if it can find one.

Closes: https://bugs.freedesktop.org/108038 Signed-off-by: Olivier Fourdan ofourdan@redhat.com