Should fix compilation error on Linux.

src/FaustEngine.cpp

@@ -182,7 +182,7 @@ struct RackUI : public GenericUI
     
     void addSoundfile(const char* label, const char* soundpath, Soundfile** sf_zone)
     {
-        WARN("Faust Prototype : 'soundfile' primitive not yet supported");
+        WARN("Faust Prototype : 'soundfile' primitive not yet supported", "");
     }
         
     void declare(FAUSTFLOAT* zone, const char* key, const char* val)