ext4_utils: don't leave bad image file in case of error

Bug: 13029951
Change-Id: Ibe50a503c2d3988813b362790b7fba83383fb51e
diff --git a/ext4_utils/make_ext4fs_main.c b/ext4_utils/make_ext4fs_main.c
index b6c740d..754e51f 100644
--- a/ext4_utils/make_ext4fs_main.c
+++ b/ext4_utils/make_ext4fs_main.c
@@ -203,6 +203,7 @@
 	exitcode = make_ext4fs_internal(fd, directory, mountpoint, fs_config_func, gzip,
 			sparse, crc, wipe, sehnd, verbose);
 	close(fd);
-
+	if (exitcode && strcmp(filename, "-"))
+		unlink(filename);
 	return exitcode;
 }