Don't require GConf2
    
    Turned out that wxWidgets doesn't use it anymore (since 2.9.3 times).
    
    See commit wxWidgets/wxWidgets#3fb71b017d051378ac30620975039beb3c33af67
    for further details.
    
    Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>