cpio: internalize archive_xread_all_eof. add a few paranoia checks

cpio: internalize archive_xread_all_eof. add a few paranoia checks
 for corrupted cpio files.
modprobe-small: remove stray include
route: small code shrink

function                                             old     new   delta
get_header_cpio                                      958     980     +22
archive_xread_all_eof                                 33       -     -33
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/0 up/down: 22/-33)            Total: -11 bytes