progress line -- cleanup until the end of line

now (0.32.5-1) progress line might look like

```
in @ 2045 kiB/s, out @ 2045 kiB/s, 18.5 GiB total, buffer 100% fullll
```
because numbers might vary in width and we keep accumulating those "l"s at the end.

Solution could probably be use of ANSI character `\033[0K`, e.g.

```shell
❯ for n in 123 23 1; do echo -ne "\rline $n"; done; echo
line 133
❯ for n in 123 23 1; do echo -ne "\rline $n\033[0K"; done; echo
line 1
```
my perl is so bad that I didn't decide to try for a PR... actually I did but failed to find code where to add ;-)