Improve error logging and handling

If we see an IO anomaly, make sure we dump as much info about the
filename, size, offset, etc.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index 9b8bed7..daf316b 100644
--- a/fio.h
+++ b/fio.h
@@ -672,6 +672,7 @@
 extern long __must_check io_u_sync_complete(struct thread_data *, struct io_u *);
 extern long __must_check io_u_queued_complete(struct thread_data *, int);
 extern void io_u_queued(struct thread_data *, struct io_u *);
+extern void io_u_log_error(struct thread_data *, struct io_u *);
 extern void io_u_init_timeout(void);
 extern void io_u_set_timeout(struct thread_data *);