[Bug-wget] bugfix #21318: "summary message for failed downloads"

[Reto Hablützel]

Hello

I would like to fix bug
#21318<https://savannah.gnu.org/bugs/?func=detailitem&item_id=21318>
.

I suggest to do it the following way when a download fails and two are
successful (like in the reproducer sample in the bug report):

Downloaded: 2 files, 15K in 0,07s (199 KB/s)
Failed: 1 file

Or shall I include the name of the file?

Please let me know if I can start and what you think about the summary
message I suggested.

Thanks,
Reto