test_unistd_close_noderawfs is flaky

[sbc100]

I've seen occasional flakes with Aborted(Assertion failed: File descriptors should not leak).

e.g. https://app.circleci.com/pipelines/github/emscripten-core/emscripten/20824/workflows/bcd8bc1b-c2f8-459f-91e0-7fb51f45554c/jobs/528170

[sbc100]

@kleisauke I think you wrote that test.. any idea how it could fail like that intermittently?

[kleisauke]

It seems that the test should exclude any unrelated file descriptors. I just opened PR #16888.

Here's an example assertion failure that would occur prior to #16795:

RuntimeError: Aborted(Assertion failed: File descriptors should not leak. 
Pre: 
/tmp/emscripten_test_other_aebh8lz7/stdout
/tmp/emscripten_test_other_aebh8lz7/stdout
Post: 
/tmp/emscripten_test_other_aebh8lz7/stdout
/tmp/emscripten_test_other_aebh8lz7/stdout
/tmp/emscripten_test_other_aebh8lz7
)

(note that I'm not sure why /stdout seems to be opened twice)

So, the file descriptor open()'d here:

emscripten/tests/unistd/close.c

Line 15 in 251ef37

int f = open(".", O_RDONLY);

Was leaking when building with -sNODERAWFS.