Fix vet errors about unkeyed fields

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Fix vet errors in aufs.go about Lock by value

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Fix vet errors about formatting directives

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Fix vet errors about json tags for unexported fields

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Merge pull request #9643 from LK4D4/fix_vet_errors

Fix vet errors