convert the barrier pshared option back to 0/1 values when getting it

src/thread/pthread_barrierattr_getpshared.c

@@ -2,6 +2,6 @@
 
 int pthread_barrierattr_getpshared(const pthread_barrierattr_t *a, int *pshared)
 {
-	*pshared = *a;
+	*pshared = !!*a;
 	return 0;
 }