Fix hang when completing a file transfer over XMPP
Review Request #1466 — Created May 21, 2022 and submitted — Latest diff uploaded
The way purple_xfer_drain_socket was implemented, if the peer never close()d the connection, we would wait forever for it to be closed remotely, causing Pidgin to hang.
Tested IRC and XMPP on Windows and Linux. Transferred big and small files.