osc: fix rare stack overflow when changing visibility mode

Under some conditions, hide_osc() was calling render(), which then called
hide_osc() again, and so forth, until the stack overflows.

Tracking the exact conditions where this happens (and then managing them
to prevent it) is an excercise in futility.

Remove the osc directly - instead of going through the entire rendering
procedure just to end up rendering nothing.

Fixes #4900 .

player/lua/osc.lua

@@ -1894,7 +1894,7 @@ function hide_osc()
         -- no-op and won't render again to remove the osc, so do that manually.
         state.osc_visible = false
         timer_stop()
-        render() -- state.osc_visible == false -> remove the osc from screen
+        render_wipe()
     elseif (user_opts.fadeduration > 0) then
         if not(state.osc_visible == false) then
             state.anitype = "out"
@@ -1973,6 +1973,11 @@ function request_init()
     state.initREQ = true
 end
 
+function render_wipe()
+    msg.debug("render_wipe()")
+    mp.set_osd_ass(0, 0, "{}")
+end
+
 function render()
     msg.debug("rendering")
     local current_screen_sizeX, current_screen_sizeY, aspect = mp.get_osd_size()