Disable temporarily guile support
    
    guile 2.0 currently fails to build from source so it is not possible to
    get it to use readline 8.0.
    
    Let's disable guile support until GDB will be ported to 2.2[0] or 2.0
    build will be fixed[1].
    
    [0] https://sourceware.org/bugzilla/show_bug.cgi?id=21104
    [1] https://bugzilla.redhat.com/show_bug.cgi?id=1675089
    
    Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>