It includes speed optimizations for HANDLER READ by caching as much as possible in HANDLER OPEN
Other things:
- Added mysqld option --disable-thr-alarm to be able to benchmark things without thr_alarm
- Changed 'Locked' state to 'System lock' and 'Table lock' (these where used in the code but never shown to end user)
- Better error message if mysql_install_db.sh fails
- Moved handler function prototypes to sql_handler.h
- Remove not anymore used 'thd->locked' member


include/thr_alarm.h:
  Added my_disable_thr_alarm
include/thr_lock.h:
  Add new member to THR_LOCK_DATA to remember original lock type state. This is needed as thr_unlock() resets type to TL_UNLOCK.
mysql-test/include/check_no_concurrent_insert.inc:
  Locked -> Table lock
mysql-test/include/handler.inc:
  Locked -> Table lock
mysql-test/r/handler_innodb.result:
  Updated results for new tests
mysql-test/r/handler_myisam.result:
  Updated results for new tests
mysql-test/r/sp-threads.result:
  Locked -> Table lock
mysql-test/suite/binlog/t/binlog_stm_row.test:
  Locked -> Table lock
mysql-test/suite/funcs_1/datadict/processlist_val.inc:
  Locked -> Table lock
mysql-test/suite/pbxt/t/lock_multi.test:
  Locked -> Table lock
mysql-test/suite/sys_vars/r/concurrent_insert_func.result:
  Locked -> Table lock
mysql-test/suite/sys_vars/t/concurrent_insert_func.test:
  Locked -> Table lock
mysql-test/suite/sys_vars/t/delayed_insert_limit_func.test:
  Locked -> Table lock
mysql-test/suite/sys_vars/t/query_cache_wlock_invalidate_func.test:
  Locked -> Table lock
mysql-test/suite/sys_vars/t/sql_low_priority_updates_func.test:
  Locked -> Table lock
mysql-test/t/insert_notembedded.test:
  Locked -> Table lock
mysql-test/t/lock_multi.test:
  Locked -> Table lock
mysql-test/t/merge-big.test:
  Locked -> Table lock
mysql-test/t/multi_update.test:
  Locked -> Table lock
mysql-test/t/query_cache_28249.test:
  Locked -> Table lock
mysql-test/t/sp_notembedded.test:
  Locked -> Table lock
mysql-test/t/sp_sync.test:
  Locked -> Table lock
mysql-test/t/status.test:
  Locked -> Table lock
mysql-test/t/trigger_notembedded.test:
  Locked -> Table lock
mysys/thr_alarm.c:
  Added option to disable thr_alarm
mysys/thr_lock.c:
  Detect loops
scripts/mysql_install_db.sh:
  Give better error message if something goes wrong
sql/Makefile.am:
  Added sql_handler.h
sql/lock.cc:
  Split functions to allow one to cache value if store_lock() (for HANDLER functions).
  - Split mysql_lock_tables() into two functions, where first one allocates MYSQL_LOCK and other other one uses it.
  - Made get_lock_data() an external function.
  - Added argument to mysql_unlock_tables() to not free sql_lock.
  - Added argument to reset_lock_data() to reset lock structure to initial state (as after get_lock_data())
sql/mysql_priv.h:
  Moved handler function prototypes to sql_handler.h
  Added new lock functions.
sql/mysqld.cc:
  Added --thread-alarm startup option
sql/net_serv.cc:
  Don't call vio_blocking() if not needed
sql/sql_base.cc:
  include sql_handler.h
sql/sql_class.cc:
  include sql_handler.h
  Remove not anymore used 'thd->locked' member
sql/sql_class.h:
  Remove not anymore used 'thd->locked' member
sql/sql_db.cc:
  include sql_handler.h
sql/sql_delete.cc:
  include sql_handler.h
sql/sql_handler.cc:
  Rewrote all code to use SQL_HANDLER instead of TABLE_LIST (original interface)
  Rewrote mysql_ha_open() to cache all things from TABLE_LIST and items for field list, where etc.
  In mysql_ha_open() also cache MYSQL_LOCK structure from get_lock_data().
  Split functions into smaller sub functions (needed to be able to implement mysql_ha_read_prepare())
  Added mysql_ha_read_prepare() to allow one to prepare HANDLER READ.
sql/sql_handler.h:
  Interface to sql_handler.cc
sql/sql_parse.cc:
  include sql_handler.h
sql/sql_prepare.cc:
  Added mysql_test_handler_read(), prepare for HANDLER READ
sql/sql_rename.cc:
  include sql_handler.h
sql/sql_show.cc:
  Removed usage of thd->locked
sql/sql_table.cc:
  include sql_handler.h
sql/sql_trigger.cc:
  include sql_handler.h