Ensure rpc_pipefs is mounted

While on some systems (like Fedora) rpc_pipefs is mounted
automatically when sunrpc module is loaded, on Debian based systems it
needs to be mounted manually.

modules.d/95nfs/nfsroot

@@ -90,6 +90,9 @@ options=${options:+$options,}$nfsrw
 [ -x /sbin/rpcbind ] && [ -z "$(pidof rpcbind)" ] && rpcbind
 
 if [ "$nfs" = "nfs4" ]; then
+    [ ! -d /var/lib/nfs/rpc_pipefs/nfs ] && \
+         mount -t rpc_pipefs rpc_pipefs /var/lib/nfs/rpc_pipefs
+
     # Start rpc.statd as mount won't let us use locks on a NFSv4
     # filesystem without talking to it. NFSv4 does locks internally,
     # rpc.lockd isn't needed