selftests/nolibc: support two errnos with EXPECT_SYSER2()

Some functions may be implemented with different syscalls in different
platforms, these syscalls may set different errnos for the same
arguments, let's support such cases.

Suggested-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/linux-riscv/20230528113325.GJ1956@1wt.eu/


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