tools/nolibc: add support for waitid()

waitid() is the modern variant of the family of wait-like syscalls.
Some architectures have dropped support for wait(), wait4() and waitpid()
but all of them support waitid().
It is more flexible and easier to use than the older ones.

Link: https://lore.kernel.org/r/20241221-nolibc-rv32-v1-1-d9ef6dab7c63@weissschuh.net


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>