pytalloc: Port to Python 3

pytalloc: Port to Python 3

- Use native string for repr

- Use rich comparison
  Removes the deprecated tp_compare in favor of tp_richcompare.
  Disparate types cannot be compared (except for == and !=),
  and True or False objects are returned explicitly.

- Use Py_TYPE instead of ob_type
  This changed to conform to C aliasing rules,
  see http://legacy.python.org/dev/peps/pep-3123/

- Don't provide CObject creation function
  A PyCapsule based replacement would be possible,
  but might not be necessary considering the function is
  not used much.

- Use new-style module initialization

Build changes:

- Use ABI flag in the lib name and pkg-config template

- Use the SAMBA_CHECK_PYTHON macro for finding Python

Signed-off-by: Petr Viktorin <pviktori@redhat.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Jelmer Vernooij <jelmer@samba.org>