This test was buggy. The first call to k_thread_abort() would
terminate the calling thread (because it handled a panic!) and so the
second case (an essential thread self-aborting) wasn't actually being
exercised and was silently "passing". Oops.
Fix by splitting the cases into two tests, as suggested by @fsammoura
But unmasking that shows that there are some arch buglets[1] to fix
before this case can pass for everyone. So skip on x86/riscv/sparc
for now.
[1] See the comment. It's not really a "bug" as we've never demanded
that arch layers do this. But it does work on many of them.
Signed-off-by: Andy Ross <andyross@google.com>
706dd25561