Get rid of no longer used mutex

This was left over from a very early version of yabridge. It's not
needed since we have to initialize all VST2 plugins from the same thread
anyways.

src/wine-host/bridges/vst2.cpp

@@ -31,11 +31,6 @@ using VstEntryPoint = AEffect*(VST_CALL_CONV*)(audioMasterCallback);
  * from an `AEffect` when it performs a host callback during its initialization.
  */
 Vst2Bridge* current_bridge_instance = nullptr;
-/**
- * Needed for the rare event that two plugins are getting initialized at the
- * same time.
- */
-std::mutex current_bridge_instance_mutex;
 
 /**
  * Opcodes that should always be handled on the main thread because they may
@@ -101,12 +96,10 @@ Vst2Bridge::Vst2Bridge(MainContext& main_context,
 
     sockets.connect();
 
-    // Initialize after communication has been set up
+    // Initialize after communication has been set up We'll try to do the same
-    // We'll try to do the same `get_bridge_instance` trick as in
+    // `get_bridge_instance` trick as in `plugin/bridges/vst2.cpp`, but since
-    // `plugin/plugin.cpp`, but since the plugin will probably call the host
+    // the plugin will probably call the host callback while it's initializing
-    // callback while it's initializing we sadly have to use a global here.
+    // we sadly have to use a global here.
-    {
-        std::lock_guard lock(current_bridge_instance_mutex);
     current_bridge_instance = this;
     plugin = vst_entry_point(host_callback_proxy);
     if (!plugin) {
@@ -117,7 +110,6 @@ Vst2Bridge::Vst2Bridge(MainContext& main_context,
     // We only needed this little hack during initialization
     current_bridge_instance = nullptr;
     plugin->ptr1 = this;
-    }
 
     // Send the plugin's information to the Linux VST plugin. Any other updates
     // of this object will be sent over the `dispatcher()` socket. This would be