Function xc2par::try_assign_fb

pub fn try_assign_fb(
    g: &InputGraph, 
    go: &mut OutputGraph, 
    mc_assignments: &[[(PARMCAssignment, PARMCAssignment); 16]], 
    fb_i: u32, 
    constraint_violations: &mut HashMap<(u32, u32, bool), u32>, 
    device_type: XC2DeviceSpeedPackage
) -> Option<PARZIAAssignment>