cpio: add support for --renumber-inodes like GNU cpio

The --renumber-inodes option renumbers the inodes starting from 1,
so that the sequence of inodes is always stable.  This helps with
reproducibility.

function                                             old     new   delta
cpio_o                                               961    1045     +84
.rodata                                            78422   78440     +18
bbconfig_config_bz2                                 6168    6164      -4
packed_usage                                       25764   25756      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 102/-12)            Total: 90 bytes

Signed-off-by: Ariadne Conill <ariadne@dereferenced.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>