Process accounting changes

The accounting changes discussed in arch_at_ about a month ago are now part 
of the CURRENT tree.  The changes increase the precision of the time 
values stored in acct(5) from 15ms (which for most commands was too 
large) to 1 microsecond.  The userland programs sa(8) and lastcomm(1) 
provide backward compatibility with existing record and file formats 
(including accounting files including both old and new records); 
regression tests are included to verify this.  The changes have been 
tested on i386, amd64, and (partly) sparc64; please drop me an email if 
you suspect a problem with your particular setup.

Many thanks to Garance A Drosehn, Bruce Evans, Peter Jeremy, 
Poul-Henning Kamp, Sam Leffler, Rick C. Petty, Erik Trulsson, and Robert 
Watson for their earlier comments; to Eric Anderson, Carl Johan 
Gustavsson, Larry Rosenman, and Derek Tattersall for responding to my 
hackers_at_ request with test data, and especially to Larry Rosenman for 
arranging access to an additional test machine.

Diomidis Spinellis - http://www.spinellis.gr