e2fsck: use ext2fs_get_mem() instad of ext2fs_get_memalign()

e2fsck: use ext2fs_get_mem() instad of ext2fs_get_memalign()

There is no reason to request a aligned buffer in
check_{inode,block}_bitmap, and this will cause failures for dietlibc,
which doesn't have support for posix_memalign() or any other way to
request an aligned memory allocation.  Fortunately, this is only
needed in very few places where direct I/O is required.

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