Make the packaging of VBOOT_SIGNER tools conditional. am: 5e04c38bbd am: 36846f0b53 am: 9084561e77 am: aaadc6dddf am: 00fe184be3
am: 4df32cb42a

Change-Id: Icd6d3a329f7f20ff5a0b412c3b3999823fb2268c