These two tests always fail when the program is started natively as an
unprivileged user, and require the user to carefully check the output
of "make run-user" and ignore them.

Let's add an euid check and condition these two tests to euid==0. Now
the test case stops needlessly reporting failures. E.g.:

  $ make -C tools/testing/selftests/nolibc run-user
  ...
    CC      nolibc-test
  123 test(s) passed.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>