Merge branch '2019-12-06-master-imports'

- Allow for the sysboot command, which is used to parse extlinux.conf
  files to be used without PXE support.  There is no functional change
  here aside from fixing distro boot in a few cases where we actually
  lacked the ability to parse the extlinux.conf file
- Add the x509/pkcs7 parsers from Linux, a pre-requisite to EFI Secure
  Boot support.