Anatol Pomozov authored Apr 13, 2020 and Allan McRae committed May 09, 2020

curl_multi_download_internal() is the main loop that creates up to
'ParallelDownloads' easy curl handles, adds them to mcurl and then
performs curl execution. This is when the paralled downloads happens.
Once any of the downloads complete the function checks its result.
In case if the download fails it initiates retry with the next server
from payload->servers list. At the download completion all the payload
resources are cleaned up.

curl_multi_check_finished_download() is essentially refactored version of
curl_download_internal() adopted for multi_curl. Once mcurl porting is
complete curl_download_internal() will be removed.

Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>