Fuse update wait thread and update thread:

Fuse update wait thread and update thread:
(update_main): No longer a thread entry point.  Remove the parameter.
Remove *player setup.  Don't terminate the thread when done.
(update_pending): Move to src/server/update.c.
(update_wait): Call update_main() instead of running it in its own
thread.  Set up *player for it.
(update_init): Create the fused update thread instead of the update
wait thread.