Upgrade TL_WRITE_CONCURRENT_INSERT to TL_WRITE_LOW_PRIORITY if

--low-priority-updates is used and the file has holes.


Docs/manual.texi:
  Changelog
sql/sql_insert.cc:
  Fixed that sleeptime is 0 for new insert delayed threads.

sql/sql_insert.cc

@@ -871,6 +871,7 @@ static pthread_handler_decl(handle_delayed_insert,arg)
   /* Add thread to THD list so that's it's visible in 'show processlist' */
   pthread_mutex_lock(&LOCK_thread_count);
   thd->thread_id=thread_id++;
+  thd->end_time();
   threads.append(thd);
   pthread_mutex_unlock(&LOCK_thread_count);