This patch contains the changes to support 48-bit block numbers in
extents.

This patch is not complete, the new function block_iterate_extents() was
not updated.

  e2fsck/pass1.c            |   15 +++++++++------
  lib/ext2fs/bmap.c         |    6 +++---
  lib/ext2fs/ext3_extents.h |   30 ++++++++++++++++++++++++++++++
  lib/ext2fs/extent.c       |   16 ++++++----------
  4 files changed, 48 insertions(+), 19 deletions(-)