Fix header output when -P is specified and (ncpus - 1) != maxid.

Reported by:	Hiroaki Shimizu
PR:		152738
Fix a bug which could break extended attributes in a dump output.
This occurred when a file was >892kB long and had a large data (>1kB)
in the extended attributes.

Reported by:	Masashi Toriumi
Reviewed by:	mckusick