fix syscall argument bug in pthread_getschedparam

the address of the pointer to the sched param, rather than the
pointer, was being passed to the kernel.

src/thread/pthread_getschedparam.c

@@ -7,7 +7,7 @@ int pthread_getschedparam(pthread_t t, int *restrict policy, struct sched_param
 	if (t->dead) {
 		r = ESRCH;
 	} else {
-		r = -__syscall(SYS_sched_getparam, t->tid, &param);
+		r = -__syscall(SYS_sched_getparam, t->tid, param);
 		if (!r) {
 			*policy = __syscall(SYS_sched_getscheduler, t->tid);
 		}