of log reset condition.


sql/log.cc:
  Added references counter of binlog readers to wait for closing opened log
  files by al readers for binary log reset.
sql/slave.cc:
  Added a code to close opened relay log files, when they are not used anymore.
sql/sql_class.h:
  Added declarations to maintain references count of binlog readers.
  Added reset log wait condition.
sql/sql_repl.cc:
  Added code to close active log files in case of log reset condition.