Don't store the Wine version as a field

It's only needed for the initialisation message, and it doesn't throw so
doing this later shouldn't make a difference.

src/plugin/bridges/vst2.h

@@ -172,12 +172,6 @@ class Vst2PluginBridge {
      */
     Vst2Logger logger;
 
-    /**
-     * The version of Wine currently in use. Used in the debug output on plugin
-     * startup.
-     */
-    const std::string wine_version;
-
     /**
      * The Wine process hosting the Windows VST plugin.
      *