file
      
Issuing 'FLUSH LOGS' does not close and reopen indexfile.
Instead a SEEK_SET is performed.
      
This patch makes index file to be closed and reopened whenever a
rotation happens (FLUSH LOGS is issued or binary log exceeds 
maximum configured size).

mysql-test/suite/binlog/r/binlog_delete_and_flush_index.result:
  Result file.
mysql-test/suite/binlog/t/binlog_delete_and_flush_index.test:
  Test case.
sql/log.cc:
  Added LOG_CLOSE_INDEX flag when calling MYSQL_BIN_LOG::close
  from within MYSQL_BIN_LOG::new_file_impl (which should just be
  called whenever a rotation is to happen - FLUSH LOGS issued or
  binlog size exceeds the maximum configured).