Revert "Revert "releasetools: Allow using futility-host to sign old TF.zip."" am: 77620b5a45 am: 9eea2cde67 am: 8fa3351890
am: 80e1a413e9

Change-Id: Ib2fc2bb687b0b34fb8f5725dd0d57323c6d1782e