lua: don't suspend core by default during script execution

This changes behavior somewhat. The old behavior can be restored by
running "mp.use_suspend=true". It was originally introduced for the OSC,
but I can't reproduce whatever misbehavior I was seeing.

(See mp.suspend()/resume() for explanations what the suspend mechanism
does.)

player/lua/defaults.lua

@@ -438,7 +438,7 @@ local function call_event_handlers(e)
     end
 end
 
-mp.use_suspend = true
+mp.use_suspend = false
 
 function mp.dispatch_events(allow_wait)
     local more_events = true