progress: don't print the last update on a separate line.

Curl_posttransfer is called too soon to add the final new line.
Moved the new line logic to pgrsDone as there is no more call to
update the progress status after this call.

Reported by: Dmitri Shubin <sbn_at_tbricks.com>
http://curl.haxx.se/mail/lib-2010-12/0162.html