Ticket 600 - Server should return unavailableCriticalExtension when processing a badly formed critical control
    
    Bug Description:
    
    	When the server receives a critical control and fails to process it,
    	it should return the result LDAP_UNAVAILABLE_CRITICAL_EXTENSION (RFC 4511 4.1.11).
    	The server may fails to process it because of various reasons (unable
    	to decode the control, unwilling to perform, invalid values...)
    
    Fix Description:
    	The fix consists, when an error condition is detected while processing
    	a control, to check the 'critical' flag to determine which result to return
    
    https://fedorahosted.org/389/ticket/600
    
    Reviewed by: Mark Reynolds (thanks mark for all these reviews)
    
    Platforms tested: Fedora 17
    
    Flag Day: no
    
    Doc impact: no
    
    QE impact: some acceptance tests will need changes (at least filter fltr_97 and fltr_99