Added block boolean var to second process_commands() invocation for blocking sockets
instead of always using true.  This prevents the process_commands() call from hanging
when a message is received with an empty queue after the call to xrecv() but
prior to the initial call to process_commands() invoked when ++ticks == inbound_poll_rate.
Signed-off-by: Marc Rossi <mrossi19@gmail.com>