Do not truncate integers on 32-bit systems in Rows_event_tracker

commit 3dc3ab1a introduced
Rows_event_tracker, using a mismatch of size_t (the native
register width) and my_off_t (the file offset width, usually
64 bits). Use my_off_t both in member fields and member functions.

sql/rpl_mi.h

@@ -139,11 +139,11 @@ typedef struct st_rows_event_tracker
   my_off_t first_seen;
   my_off_t last_seen;
   bool stmt_end_seen;
-  void update(const char* file_name, size_t pos,
+  void update(const char* file_name, my_off_t pos,
               const char* buf,
               const Format_description_log_event *fdle);
   void reset();
-  bool check_and_report(const char* file_name, size_t pos);
+  bool check_and_report(const char* file_name, my_off_t pos);
 } Rows_event_tracker;
 
 /*****************************************************************************

sql/slave.cc

@@ -7650,7 +7650,7 @@ void Rows_event_tracker::reset()
   well as the end-of-statement status of the last one.
 */
 
-void Rows_event_tracker::update(const char* file_name, size_t pos,
+void Rows_event_tracker::update(const char* file_name, my_off_t pos,
                                 const char* buf,
                                 const Format_description_log_event *fdle)
 {
@@ -7675,7 +7675,7 @@ void Rows_event_tracker::update(const char* file_name, size_t pos,
                 false otherwise.
 */
 bool Rows_event_tracker::check_and_report(const char* file_name,
-                                          size_t pos)
+                                          my_off_t pos)
 {
   if (last_seen)
   {