Verify that sem_wait() doesn't return zero without decrementing the
semaphore when a signal is received. It should either resume waiting
or return EINTR, preferrably the former.

While we guarantee that a zero-filled sem_t variable will trigger
EINVAL errors, a sem_t on the stack may have garbage, so make the
tests portable by moving the sem_t from function to file scope.

pr

While we guarantee that a zero-filled sem_t variable will trigger
EINVAL errors, a sem_t on the stack may have garbage, so make the
tests portable by moving the sem_t from function to file scope.

problem found by miod@

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Basic semaphore tests

ok guenther@