+/** @brief Allocate an event to be filled in by the caller, non-inline
+
+ Not normally called directly; this function underlies the
+ ELOG_DATA and ELOG_TRACK_DATA macros
+
+ @param em elog_main_t *
+ @param type elog_event_type_t * type
+ @param track elog_track_t * track
+ @param cpu_time u64 current cpu tick value
+ @returns event to be filled in
+*/