Change the "information" error to "debug" error.

There was one debugging error sent with "information" severity. That
confused the GUI that didn't know such severity. Change the severity
to "debug" so the meaning of the error is more clear.

lib/tokenize.cpp

@@ -2287,7 +2287,7 @@ void Tokenizer::simplifyTemplates()
                     locationList.push_back(loc);
 
                     const ErrorLogger::ErrorMessage errmsg(locationList,
-                                                           "information",
+                                                           "debug",
                                                            "Failed to instantiate template. The checking continues anyway.",
                                                            "templateInstantiate");