aio: fix the tests when ZFS is not available

Don't try to cleanup the zpool if we couldn't create a zpool in the
first place.

Submitted by:	tmunro
MFC-with:	022ca2fc7f

sys/contrib/openzfs/module/zfs/vdev.c

@@ -3263,6 +3263,7 @@ vdev_load(vdev_t *vd)
 
 	/*
 	 * Recursively load all children.
+	 * TODO: parallelize.
 	 */
 	for (int c = 0; c < vd->vdev_children; c++) {
 		error = vdev_load(vd->vdev_child[c]);

tests/sys/aio/aio_test.c

@@ -943,6 +943,10 @@ aio_zvol_cleanup(void)
 	char cmd[160];
 
 	pidfile = fopen("pidfile", "r");
+	if (pidfile == NULL && errno == ENOENT) {
+		/* Setup probably failed */
+		return;
+	}
 	ATF_REQUIRE_MSG(NULL != pidfile, "fopen: %s", strerror(errno));
 	ATF_REQUIRE_EQ(1, fscanf(pidfile, "%d", &testpid));
 	fclose(pidfile);