Store context menu items in unordered maps

The difference in performance won't be noticable, but both lookups and
modifications in these things are much faster once you have more than
one or two elements.

src/wine-host/bridges/vst3-impls/context-menu-proxy.h

@@ -55,7 +55,8 @@ class Vst3ContextMenuProxyImpl : public Vst3ContextMenuProxy {
      * The targets passed when to `addItem` calls made by the plugin. This way
      * we can call these same targets later. The key here is the item's tag.
      */
-    std::map<int32, Steinberg::IPtr<Steinberg::Vst::IContextMenuTarget>>
+    std::unordered_map<int32,
+                       Steinberg::IPtr<Steinberg::Vst::IContextMenuTarget>>
         context_menu_targets;
 
    private: