The first parameter to both functions is a pointer to the set of attributes for
the thread.
The second parameter is either (1) a pointer to an integer that is
set to the current scheduling policy (for pthread attr getsched policy())
or (2) an integer value (SCHED FIFO, SCHED RR, or SCHED OTHER) for the
pthread attr setsched policy() function.
Both functions return nonzero values if an error occurs.