sbverify: Clear out content for the signature we're building

OpenSSL 1.0.2e now actively checks for both data and contents being present
for a certificate. Clear out contents so that we have only data, and run a
chance of actually verifying the signature.

Bug-Ubuntu: https://launchpad.net/bugs/1526959
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
1 file changed