Extend ipo file action capabilities

Add FIO_LOG_UNLINK_FILE and move the handling of special ipo's
into a dedicated function.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index dab66d2..34f02d6 100644
--- a/fio.h
+++ b/fio.h
@@ -755,6 +755,7 @@
 	FIO_LOG_ADD_FILE,
 	FIO_LOG_OPEN_FILE,
 	FIO_LOG_CLOSE_FILE,
+	FIO_LOG_UNLINK_FILE,
 };
 
 extern int __must_check read_iolog_get(struct thread_data *, struct io_u *);