In line to what is done in UFS, define an internal type
e2fs_lbn_t for the logical block numbers.
This change is basically a no-op as the new type is unchanged
(int32_t) but it may be useful as bumping this may be required
for ext4fs.
Also, as pointed out by Bruce Evans:
-Use daddr_t for daddr in ext2_bmaparray(). This seems to
improve reliability with the reallocblks option.
- Add a cast to the fsbtodb() macro as in UFS.
Reviewed by: bde
MFC after: 3 days