Update to efivar 31
- Work around NVMe EUI sysfs change
- Provide some oldish version strings we should have kept.
- lots of overflow checking on our pointer math in dp parsing
- fix major/minor device number handling in the linux code
- Do better formatting checks for MBR partitions
- Fixes for gcc 7
Signed-off-by: Peter Jones <pjones@redhat.com>