Bug #18559 "log tables cannot change engine, and
            gets deadlocked when dropping w/ log on":
1) Add more generic error messages
2) Add new handlerton flag for engines, which support
   log tables
3) Remove (log-tables related) mutex lock in myisam to
   improve performance


mysql-test/r/log_tables.result:
  update result file to use new error messages
mysql-test/t/log_tables.test:
  update test file with new error messages
sql/handler.h:
  Add new handlerton flag, to mark whether engine
  supports log tables
sql/share/errmsg.txt:
  Add more generic error messages
sql/sql_table.cc:
  Update error messages
storage/csv/ha_tina.cc:
  CSV supports log tables
storage/myisam/ha_myisam.cc:
  MyISAM supports log tables
storage/myisam/mi_write.c:
  remove mutex lock to improve performance