busybox

mkfs_ext2: fixes for huge filesystems

function                                             old     new   delta
mkfs_ext2_main                                      2145    2617    +472
div_roundup                                           15      35     +20
packed_usage                                       26792   26776     -16

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>