QUIC: optimized immediate close. Previously, before sending CONNECTION_CLOSE to client, all pending frames were sent. This is redundant and could prevent CONNECTION_CLOSE from being sent due to congestion control. Now pending frames are freed and CONNECTION_CLOSE is sent without congestion control, as advised by RFC 9002: Packets containing frames besides ACK or CONNECTION_CLOSE frames count toward congestion control limits and are considered to be in flight.

setlocal commentstring=#\ %s