e2fsck: make block counting variable in pass1 64 bits

e2fsck: make block counting variable in pass1 64 bits

Justin reported that creating a 4T file with posix_fallocate led
to fsck errors:

e2fsck 1.41.10 (10-Feb-2009)
Pass 1: Checking inodes, blocks, and sizes
Inode 12, i_blocks is 8589935432, should be 840.  Fix? yes

This looks like a 32-bit overflow.

commmit 8a8f36540bbf5d4397cf476e216e9a720b5c1d8e added handling of
the high i_blocks number, but we accumulate blocks in the num_blocks
field, and that's still just 32 bits.

Note: we don't need to expand max_blocks for now, that's only used
in the non-extents case, and those files have smaller max sizes.

I haven't been able to replicate the problem, oddly, but Justin
reports that this patch fixed his situation.

Reported-by: Justin Maggard <jmaggard10@gmail.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>