libext2fs: fix the range validation in bitmap_range2 funcs

libext2fs: fix the range validation in bitmap_range2 funcs

The condition ((start+num) & ~0xffffffffULL) in bitmap_range2
and generic_bmap_range funcs in get_bitmap64.c was wrong and
inconsistent with the condition (start+num-1 > bmap->real_end)
in generic_bitmap_range funcs in get_bitmap.c.

I got the following error from tune2fs on a 16TB fs:
Illegal block number passed to ext2fs_unmark_block_bitmap #4294967295
for block bitmap for 16TB.img
tune2fs: Invalid argument while reading bitmaps

Fix to condition to ((start+num-1) & ~0xffffffffULL), because
the bit (start+num) is not going to be changed by the funcs.

Signed-off-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>