ndb - fixed for BUG#15021, binlog_index table become inconsistent if errors during purge of binlogs.
if EMFILE error occured while purging binary logs, stop purging logs and report error message to user.


mysys/my_open.c:
  report EMFILE error when opening file failed.
sql/log.cc:
  report EMFILE error when purging logs, and stop purging logs when EMFILE error occured.
sql/log.h:
  added LOG_INFO_EMFILE error number.
sql/share/errmsg.txt:
  added EMFILE error message for purging binary logs.
sql/sql_repl.cc:
  added EMFILE error message.
sql/table.cc:
  report EMFILE error.