Raises
```
/Users/john/Development/gtk-sources/gnucash-git/src/libqof/qof/test/test-gnc-guid.cpp:79:21: error: format
      string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
    g_test_message (message.c_str ());
```
Easily fixed by changing to ```g_test_message ("%s", message.c_str ());```