manual.texi preliminary fixups to XOR, CHECK_LOCK() change notes.

The one that with a query like :

select 11 ^ 3;

@example

SELECT 11 ^ 3;

@end example

returns 8.

Based on the code originated  by Hartmut Holzgraefe <hartmut@six.de>.

Based on code contributed by Hartmut Holzgraefe @email{hartmut@@six.de}.

@item

Added logical XOR.

The one that with a query like:

select 1 XOR 1;

@example

SELECT 1 XOR 1;

@end example

returns 0;

Based on the code originated by Hartmut Holzgraefe <hartmut@six.de>.

Based on code contributed by Hartmut Holzgraefe @email{hartmut@@six.de}.

@item

Add function CHEDK_LOCK("lock_name"). 

This function checks if the lock of the certain name is available or not. 

This function does not attempt to take a look.

Add function @code{CHECK_LOCK("lock_name")}. 

This function returns a value indicating whether or not the lock with the

given name is available. 

It does not attempt to acquire a lock.

It is used like this:

@example

SELECT CHECK_LOCK("some_lock");

@end example

it will return 1 if the lock is held by a process (including by

itself), 0 if it is currently not held by anyone and NULL on

errors.

Based on the code originated  by Hartmut Holzgraefe <hartmut@six.de>.

@code{CHECK_LOCK()} returns 1 if the lock is available,

0 if the lock is held by any process (including the current process),

and @code{NULL} if an error occurs.

Based on code contributed by Hartmut Holzgraefe @email{hartmut@@six.de}.

@item

Removed @code{mysql_ssl_clear()}, as this was not needed.

@item