dvd, bd, osc: disable OSC while a menu is active

They interfere.

It turns out that commit b6ca4a48 actually broke this in weird ways, but
this solution is better anyway.

player/lua/osc.lua

@@ -1876,6 +1876,15 @@ mp.observe_property("fullscreen", "bool", function(name, val) state.fullscreen =
 mp.observe_property("pause", "bool", pause_state)
 mp.observe_property("cache-idle", "bool", cache_state)
 
+mp.observe_property("disc-menu-active", "bool", function(name, val)
+    if val == true then
+        hide_osc()
+        mp.disable_key_bindings("showhide")
+    else
+        mp.enable_key_bindings("showhide")
+    end
+end)
+
 -- mouse show/hide bindings
 mp.set_key_bindings({
     {"mouse_move",              function(e) process_event("mouse_move", nil) end},