MODSIGN: Allow the "db" UEFI variable to be suppressed

MODSIGN: Allow the "db" UEFI variable to be suppressed

If a user tells shim to not use the certs/hashes in the UEFI db variable
for verification purposes, shim will set a UEFI variable called
MokIgnoreDB.  Have the uefi import code look for this and ignore the db
variable if it is found.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Gbp-Pq: Topic features/all/db-mok-keyring
Gbp-Pq: Name 0005-MODSIGN-Allow-the-db-UEFI-variable-to-be-suppressed.patch