Following usecase:
call efl_del in a event handler from EFL_EVENT_NOREF. What then happens
is that efl_unref happens while unref_compesate is EINA_TRUE.
This means that _efl_unref is not called. (The unref to the _efl_ref call from efl_ref).
however, in the call to efl_unref where EFL_EVENT_NOREF is called,
_efl_unref is also not called because user_refcount is already 0
before, so the dec leads to a negative value.
Depends on D6244