make aio_suspend a cancellation point and properly handle cancellation

src/aio/aio_suspend.c

@@ -15,6 +15,8 @@ int aio_suspend(const struct aiocb *const cbs[], int cnt, const struct timespec
 	int nzcnt = 0;
 	const struct aiocb *cb = 0;
 
+	pthread_testcancel();
+
 	if (cnt<0) {
 		errno = EINVAL;
 		return -1;
@@ -61,10 +63,14 @@ int aio_suspend(const struct aiocb *const cbs[], int cnt, const struct timespec
 			break;
 		}
 
-		ret = __timedwait(pfut, expect, CLOCK_MONOTONIC, ts?&at:0, 1);
+		ret = __timedwait_cp(pfut, expect, CLOCK_MONOTONIC, ts?&at:0, 1);
 
-		if (ret) {
-			errno = ret==ETIMEDOUT ? EAGAIN : ret;
+		switch (ret) {
+		case ETIMEDOUT:
+			ret = EAGAIN;
+		case ECANCELED:
+		case EINTR:
+			errno = ret;
 			return -1;
 		}
 	}