Comment 5 for bug 1665355

Finally, I think I found the cause (as the problem appeared on Debian as well): The object file pythongdl.cpp.o was empty, and all functions (including initGDL and PyInit) were called from the library (libgnudatalanguage0) linked to. On gcc-9 (and probably on Ubuntu's gcc), the "as-needed" flag is implicite in the linking step, which prevents unneded libraries from being linked. Therefore, the symbols can't befound anymore.

This is now solved in the Debian package.