Btrfs-progs: fix magic return value in send-test.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

send-test.c

@@ -454,5 +454,5 @@ int main(int argc, char **argv)
 
 	pthread_attr_destroy(&t_attr);
 out:
-	return ret;
+	return !!ret;
 }