BUG#23171 (Illegal slave restart group position):

First patch preparing for restructuring the event execution and event
skipping. This patch renames the existing (virtual) function exec_event()
to be a primitive for implementing the real patch. Also, the virtual function
advance_coord_impl() is added to advance the binary/relay log coordinates,
and two non-virtual functions exec_event() [sic] and skip_event() is added
that will contain the business logic for executing and skipping events
respectively.


sql/log.cc:
  Renaming exec_event()
sql/log_event.cc:
  Renaming exec_event()
sql/log_event.h:
  Renaming exec_event() to apply_event_impl()
  Addng new non-virtual exec_event() that will contain business logic
  for event execution.
  Adding new non-virtual skip_event() that will contain business logic
  for skipping an event.
  Adding new virtual advance_coord_impl() as primitive to advance
  binary/relay log coordinates according to the event's needs.

sql/log.cc

@@ -2411,7 +2411,7 @@ bool MYSQL_BIN_LOG::open(const char *log_name,
       /*
         Set 'created' to 0, so that in next relay logs this event does not
         trigger cleaning actions on the slave in
-        Format_description_log_event::exec_event().
+        Format_description_log_event::apply_event_impl().
       */
       description_event_for_queue->created= 0;
       /* Don't set log_pos in event header */