(VERBOSE_UPDATE): Now counts seconds, not bytes.

(VERBOSE_UPDATE): Now counts seconds, not bytes.

(dopass): If verbose, output a line every VERBOSE_UPDATE seconds,
and suppress duplicate output lines.  Output a percentage as well
as a count of bytes.

Also, fix comment/code typo regarding how many bytes have been
written; this typo was harmless before, but is no longer harmless with
the above change in effect.