Rebase to upstream snapshot.
    
    - Fix PPC build error (#967862)
    - Fix crash on net_bootp command (#960624)
    - Reset colors on ppc when appropriate (#908519)
    - Left align "Loading..." messages (#908492)
    - Fix probing of SAS disks on PPC (#953954)
    - Add support for UEFI OSes returned by os-prober
    - Disable "video" mode on PPC for now (#973205)
    - Make grub fit better into the boot sequence, visually (#966719)