Merge efilib changes from projects/uefi

r247216:

  Add the ability for a device to have an "alias" handle.

r247379:

  Fix network device registration.

r247380:

  Adjust our load device when we boot from CD under UEFI.

  The process for booting from a CD under UEFI involves adding a FAT
  filesystem containing your loader code as an El Torito boot image.
  When UEFI detects this, it provides a block IO instance that points
  at the FAT filesystem as a child of the device that represents the CD
  itself. The problem being that the CD device is flagged as a "raw
  device" while the boot image is flagged as a "logical partition".
  The existing EFI partition code only looks for logical partitions and
  so the CD filesystem was rendered invisible.

  To fix this, check the type of each block IO device. If it's found to
  be a CD, and thus an El Torito boot image, look up its parent device
  and add that instead so that the loader will then load the kernel from
  the CD filesystem.  This is done by using the handle for the boot
  filesystem as an alias.

  Something similar to this will be required for booting from other media
  as well as the loader will live in the EFI system partition, not on the
  partition containing the kernel.

r247381:

  Remove a scatalogical debug printf that crept in.