failtest: fix warning [-Wformat]

hi rusty,

here is a trival path to fix warning [-Wformat].

Thanks.
Tinggong

Signed-off-by: Tinggong <wangtinggong@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
iscsi, ttxml: fix warning [-Wunused-but-set-variable]

hi all,

here is a trival path to fix warning [-Wunused-but-set-variable].

Thanks.
Tinggong

Signed-off-by: Tinggong <wangtinggong@gmail.com>