selftests/nolibc: also count skipped and failed tests in output

Right now skipped and failed test counts are not reported, and a few
times already we missed skipped ones that ought not to. Let's now
count each category and continue to invite the user to check the
report file when skipped+fail > 0. E.g:

  $ make run-user
    (...)
    CC      nolibc-test
  136 test(s) passed, 2 skipped, 0 failed. See all results in .../run.out

Note that it's important to be careful about the trailing \r on the qemu
output (thanks Zhangjin for noticing).

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>