Fixed mutex problem when doing automatic repair of MyISAM tables


Docs/manual.texi:
  changelog
include/thr_lock.h:
  Added TL_READ_WITH_SHARED_LOCKS for Innobase
mysql-test/r/update.result:
  Added 'select' to verify update results
mysql-test/t/update.test:
  Better code coverage
mysys/getvar.c:
  Allow space in to --set-variable
mysys/thr_lock.c:
  Added TL_READ_WITH_SHARED_LOCKS
sql/ha_myisam.cc:
  Added comment
sql/lock.cc:
  Added missing broadcast
sql/sql_base.cc:
  Fixed some mutex problem when doing automatic repair of MyISAM tables
sql/sql_update.cc:
  Purecoverage