slave SQL thread is started.


sql/slave.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/slave.h:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/sql_repl.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/repl_failsafe.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.