cpio: implement -R/--owner

cpio: implement -R/--owner

Implement -R/--owner to force ownership of files.

function                                             old     new   delta
cpio_main                                            532     586     +54
get_header_cpio                                      909     939     +30
print                                                 36      65     +29
cpio_o                                               804     832     +28
cpio_TRAILER                                           -      11     +11
packed_usage                                       30667   30662      -5
static.trailer                                        11       -     -11
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 4/1 up/down: 152/-16)           Total: 136 bytes

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>