Please review changes for the Debian shim -7 upload

[Steve McIntyre <steve@einval.com>]

Hey folks,

I think I'm about ready to upload a new shim, with a number of
changes., It would be lovely to get more eyes on these, as I'm hoping
this will be our last upload before buster and I want to get this
signed.

See https://salsa.debian.org/efi-team/shim/commits/master

Changes for review:

549f650 (93sam/hack, hack) Add more hashes that we want to blacklist
88a7a65 Add initial file with test checksums for the dbx list
6cf246a Generate a vendor dbx file at build time
e17b0af Build using gcc-7
315e876 Fix OBJ_create() to tolerate a NULL sn and ln
878d860 VLogError(): Avoid NULL pointer dereferences in (V)Sprint calls

In particular, please check my logic in the dbx file creation. I've
tested this using a local VM set up with secure boot enabldd and test
keys in the firmware, and it looked to work ok.

Please review/test as soon as you can - I don't want this to be
blocking the Buster release.

-- 
Steve McIntyre, Cambridge, UK.                                steve@einval.com
"C++ ate my sanity" -- Jon Rabone