There was already a timeout set using `CURLOPT_CONNECTTIMEOUT`, but that
only affects the initial connection. Once a HTTP connection is
established, the timeout is ineffective.
That means that once a HTTP connection is established, there is no bound
on the length of time a download can take. Sometimes, downloads drop to
very low speeds (for Networking Reasons) and we need a way to give up on
a download if that happens.
So, set a low speed limit of 10KB/s for 60s. If a curl download goes
more slowly than this, it will be considered timed out, and the
`CURLE_OPERATION_TIMEDOUT` code path will be taken.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Fixes: https://github.com/flatpak/flatpak/issues/5519
(cherry picked from commit d6b10c26ef)
64da41f2b5