Ticket 49441 - Import crashes with large indexed binary
     attributes
    
    Bug Description:  Importing an ldif file that contains entries with large
                      binary attributes that are indexed crashes the server.
                      The crash occurs when "encoding" the binary value to a
                      string for debug logging, where we "underflow" the buffer
                      space index which then allows the string buffer to overflow.
    
    Fix Description:  While filling the string buffer with the encoded binary
                      value we need to make sure if the buffer space is greater
                      than zero before decrementing it.
    
                      Also check if trace logging is being used before we actually
                      call the logging function which calls the "encoded" function
                      first.  This way we avoid this costly "encoding" on every
                      index call we make.
    
    https://pagure.io/389-ds-base/issue/49441
    
    Reviewed by: firstyear(Thanks!)