spsysinit01: Fix sem_open() call

The O_CREAT flag requires a mode and initial value as third and fourth
argument.

Close #4878.

testsuites/sptests/spsysinit01/init.c

@@ -908,7 +908,7 @@ static void do_posix_sem_open(void)
   sem_t *sem;
   int rv;
 
-  sem = sem_open("sem", O_CREAT | O_RDWR, S_IRWXU | S_IRWXG | S_IRWXO);
+  sem = sem_open("sem", O_CREAT | O_RDWR, S_IRWXU | S_IRWXG | S_IRWXO, 0);
   rtems_test_assert(sem != SEM_FAILED);
 
   rv = sem_close(sem);