Remove extra new lines after GTK log messages

This seems unnecessary as the default log handler already outputs a new
line at the end of the message anyhow and at least some messages (e.g.
debug ones in GdkPixbuf) also contain an extra new line in them, so
adding another one here resulted in having at least one and sometimes
two extra blank lines.

tests/test.cpp

@@ -514,8 +514,6 @@ wxTestGLogHandler(const gchar* domain,
             wxGetCurrentTestName().c_str());
 
     g_log_default_handler(domain, level, message, data);
-
-    fprintf(stderr, "\n");
 }
 
 #endif // __WXGTK__