[ci skip] Fix broken strict option link in MySQL adapter (4-2-stable)

http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html is broken.

New link: http://dev.mysql.com/doc/refman/5.0/en/sql-mode.html

Author: JuanitoFatas

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -57,7 +57,7 @@ module ConnectionAdapters
     # * <tt>:database</tt> - The name of the database. No default, must be provided.
     # * <tt>:encoding</tt> - (Optional) Sets the client encoding by executing "SET NAMES <encoding>" after connection.
     # * <tt>:reconnect</tt> - Defaults to false (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/auto-reconnect.html).
-    # * <tt>:strict</tt> - Defaults to true. Enable STRICT_ALL_TABLES. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html)
+    # * <tt>:strict</tt> - Defaults to true. Enable STRICT_ALL_TABLES. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/sql-mode.html)
     # * <tt>:variables</tt> - (Optional) A hash session variables to send as <tt>SET @@SESSION.key = value</tt> on each database connection. Use the value +:default+ to set a variable to its DEFAULT value. (See MySQL documentation: http://dev.mysql.com/doc/refman/5.0/en/set-statement.html).
     # * <tt>:sslca</tt> - Necessary to use MySQL with an SSL connection.
     # * <tt>:sslkey</tt> - Necessary to use MySQL with an SSL connection.