Update to efibootmgr 14
    
    - Remove "(hex)" from description of --delete-bootnum
    - Fix a typo in the popt options
    - Add README.md
    - make efibootdump install by default
    - Man page fixes
    - Better compiler detection
    - Don't use --default-symver in efibootmgr
    - Make -flto part of the overrideable CFLAGS
    
    Signed-off-by: Peter Jones <pjones@redhat.com>