SSL.sslfile: close_packet_send_state is no more.

Most of the state that was kept in close_packet_send_state
is now kept in the connection state. There's also no need
to delay the queueing of the close packet until the write
queues are empty, as the packets aren't consolidated anyway.
SSL.sslfile: Restructured queue_write() somewhat.

Now delays queueing of the close packet until all application
data has been sent.
SSL.sslfile: Consolidate packets in queue_write().

queue_write() now attempts to keep ~16KB of data to send in the
write_buffer.

NB: For some reason this causes the required number of runs through the
backend during handshaking to increase somewhat.
SSL.sslfile: Write multiple packets in the same write().

Use the support for writev(2) to write the packets in the write_buffer.

This should improve data throughput measurably.

NB: This reduces the number of required rounds in the backend
during handshaking to the old level.
Removed #if 0 code.
Build: Reduce complaint about unused functions.

We don't care if inline functions defined in the header files aren't
used in all files that include them...

Reduces the number of build warnings to reasonable levels.