Slight refresh of the download progress callback

Slight refresh of the download progress callback

This cleans up some of the mess we have here.

* switch to long units for the download size
* omit the .0 decimal part from the download rate
* omit the almost always zero HH: from estimated time if eta_h == 0
* Display --:-- if eta_h > 99; formatting was screwed up before

The net result of this is we usually have 1 more character to use for
filename display.

Before:
 extra                   500.9K 1242.4K/s 00:00:00 [######################] 100%
 community-testing       947.0B   28.2M/s 00:00:00 [######################] 100%
 multilib                 26.5K  405.1K/s 00:00:00 [######################] 100%
 community               450.6K 1238.3K/s 00:00:00 [######################] 100%

After:
 extra                    500.9 KiB  1118K/s 00:00 [######################] 100%
 community-testing        947.0   B    23M/s 00:00 [######################] 100%
 multilib                  26.5 KiB   255K/s 00:00 [######################] 100%
 community                450.6 KiB  1211K/s 00:00 [######################] 100%

Signed-off-by: Dan McGee <dan@archlinux.org>