Output a zero rdev except for bdevs, cdevs, fifos and sockets. This

Output a zero rdev except for bdevs, cdevs, fifos and sockets.  This
stops regular files with unrepresentable rdevs from being rejected
and makes the output independent of unpreservable metadata.

Don't output a file if the major, minor or totality of its rdev would be
truncated.  Print a message about the skipped files to stderr but don't
report the error in the exit status.  cpio's abysmal error handling doesn't
allow continuing after an error, and the rdev checks had to be misplaced
to avoid the problem of returning an error code from routines that return
void.

Minor numbers are limited to 21 bits in pax's ustar format and to 18
bits in archives created by gnu tar (gnu tar wastes 3 bits for padding).
pax's and cpio's ustar format is incompatible with gnu tar's ustar
format for other reasons (see cpio/README).

Submitted by:	bde via old gnu/usr.bin/cpio v2.3.