Fix incorrect splitting of Python files into subpackages.
Since the -common subpackage installs files in
%{python3_sitelib}/%{name}, it should also own that directory instead of
the main package. Also, exclude files that are in subpackages from the
main package. Finally, byte-compiled files were not specified correctly
for Python 3. This was hidden in the main package glob, instead of being
in the subpackages.