Document PyImport_AppendInittab(), PyImport_ExtendInittab(), and struct _inittab.
Document PyImport_AppendInittab(), PyImport_ExtendInittab(), and
struct _inittab.

This closes SourceForge bug #111499.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator