Zabbix

........S. [ZBXNEXT-4108] added internal event processing

Inside the add_event() function, we do not need to check for the
source of the event. The error argument is set to a proper value
by the caller and all the internal event types that must not register
a 'name' field, will just pass NULL.
So, just check if the source is an internal event and if the error
message is != NULL. If so, copy it in the name field.
Also, moved the zbx_free() for the name field before the check
for the source of the event, thus we will be sure to free allocated
memory for every needed event.