Make it simpler to add events to Python

Make it simpler to add events to Python

The first patch in this series went through several iterations as I'd
forgotten how many places had to be touched to add a new event and a
new event type.

This patch simplifies the process using two new ".def" files.  Now, a
new event type can be added by adding a line to "py-event-types.def",
and a new event registry can be added by adding a line to
"py-all-events.def".

ChangeLog
2017-09-11  Tom Tromey  <tom@tromey.com>

	* python/python.c (do_start_initialization): Use
	py-event-types.def to initialize types.
	Define all object type structures.
	* python/python-internal.h: Don't declare event initialization
	functions.
	* python/py-threadevent.c (thread_event_object_type): Don't
	define.
	* python/py-stopevent.c (stop_event_object_type): Don't define.
	* python/py-signalevent.c (signal_event_object_type): Don't
	declare or define.
	* python/py-newobjfileevent.c (new_objfile_event_object_type)
	(clear_objfiles_event_object_type): Don't declare or define.
	* python/py-infevents.c (inferior_call_pre_event_object_type)
	(inferior_call_post_event_object_type)
	(register_changed_event_object_type)
	(memory_changed_event_object_type): Don't declare or define.
	* python/py-inferior.c (new_thread_event_object_type)
	(new_inferior_event_object_type)
	(inferior_deleted_event_object_type): Don't declare or define.
	* python/py-exitedevent.c (exited_event_object_type): Don't
	declare or define.
	* python/py-evts.c (gdbpy_initialize_py_events): Use
	py-all-events.def.
	* python/py-events.h (thread_event_object_type): Don't declare.
	(events_object): Use py-all-events.def.
	* python/py-event.h (GDBPY_NEW_EVENT_TYPE): Remove.  Use
	py-event-types.def.
	* python/py-event-types.def: New file.
	* python/py-continueevent.c (create_continue_event_object): Don't
	declare or define.
	* python/py-bpevent.c (breakpoint_event_object_type): Don't
	declare or define.
	* python/py-all-events.def: New file.