Fix ->file_map leak

Just to appease valgrind.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/filesetup.c b/filesetup.c
index af14c67..49c4504 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -401,6 +401,9 @@
 		}
 
 		td_io_close_file(td, f);
+
+		if (f->file_map)
+			free(f->file_map);
 	}
 
 	td->filename = NULL;