ecore: fix built-in event types generation

Summary:
Ecore internally uses 10 events, from ECORE_EVENT_SIGNAL_USER=1 to
ECORE_EVENT_SYSTEM_TIMEDATE_CHANGED=10. The Ecore.Event.Message_Handler
singleton that holds the counter of events is initialized with -1.
This is followed in _ecore_event_init() by ten calls to
ecore_event_message_handler_type_new(), which increase the counter of
event by one each.

This results in an event counter to be 9 (-1 + 10) at the end of the
initialization of ecore_events. This means that the next event to be
created will have a value of 10, which will overlap with
ECORE_EVENT_SYSTEM_TIMEDATE_CHANGED. As such, these two distinct events
will be aliased and their associated handlers will be called at
unexpected times, with unexpected data.

By changing the constructor value from -1 to 0, we prevent this event
aliasing.

Fixes T6605

Reviewers: zmike, Hermet

Reviewed By: Hermet

Subscribers: cedric, #reviewers, #committers, zmike

Tags: #efl

Maniphest Tasks: T6605

Differential Revision: https://phab.enlightenment.org/D6894

src/lib/ecore/ecore_event_message_handler.c

@@ -290,7 +290,7 @@ EOLIAN static Efl_Object *
 _ecore_event_message_handler_efl_object_constructor(Eo *obj, Ecore_Event_Message_Handler_Data *pd)
 {
    obj = efl_constructor(efl_super(obj, MY_CLASS));
-   pd->event_type_count = -1;
+   pd->event_type_count = 0;
    pd->current_event_type = -1;
    return obj;
 }