ffz() takes ints, so change the file_map to being int based

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/ioengines.c b/ioengines.c
index 662d55d..dd70e1d 100644
--- a/ioengines.c
+++ b/ioengines.c
@@ -362,7 +362,7 @@
 	}
 
 	if (f->file_map)
-		memset(f->file_map, 0, f->num_maps * sizeof(long));
+		memset(f->file_map, 0, f->num_maps * sizeof(int));
 
 done:
 	log_file(td, f, FIO_LOG_OPEN_FILE);