MAINTAINERS: nolibc: add myself as co-maintainer

As discussed with Willy, Paul and Shuah add myself as maintainer for
the nolibc subsystem.

Link: https://lore.kernel.org/lkml/7afafb6c-9664-44a1-bc8f-d20239db1dd5@paulmck-laptop/


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>