libext2fs: Add callback functions for _alloc_block() and _block_alloc_stats()

Add callback functions for ext2fs_alloc_block() and
ext2fs_block_alloc_stats().  This is needed so e2fsck can be informed
when the extent_set_bmap() function needs to allocate or deallocate
blocks.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
3 files changed