Added missing InnoDB variables to SHOW VARIABLES.
Fixed bug when doing WHERE 'column_name=NULL' on an indexed column that had NULL values.
Fixed bug when doing 'LEFT JOIN ...  ON (column_name = constant) WHERE column_name = constant'


Docs/manual.texi:
  Changelog
libmysql/libmysql.c:
  Don't use signal() on windows.
mysql-test/r/join_outer.result:
  Test for bugfix
mysql-test/r/null.result:
  Test for bugfix
mysql-test/t/join_outer.test:
  Test for bugfix
mysql-test/t/null.test:
  Test for bugfix
sql/mysqld.cc:
  Add missing InnoDB variables to SHOW VARIABLES.
sql/sql_select.cc:
  Fixed bug when doing WHERE 'column_name=NULL' on an indexed column that had NULL values.
  Fixed bug when doing 'LEFT JOIN ...  ON (column_name = constant) WHERE column_name = constant'