remove unreachable code from various compare ops

remove unreachable code from various compare ops

All the compare ops (such as pp_le), have an initial:

    tryAMAGICbin_MG(le_amg, AMGf_numeric);

The effect of the AMGf_numeric flag is that, if the le overloading fails,
but either of the args on the stack is a reference, then that arg is
replaced with a temporary non-ref arg that is either the result of
'0+' overloading, or is a UV with the numerical value of the ref's
address.  So by the time the main body of the op is called, neither arg
can be a ref.

Thus a whole bunch of nearly identical blocks can be removed, which *used*
to handle comparing refs:

    if (SvROK(TOPs) && !SvAMAGIC(TOPs) && SvROK(TOPm1s) && !SvAMAGIC(TOPm1s)) {
        SP--;
        SETs(boolSV(SvRV(TOPs) <= SvRV(TOPp1s)));
        RETURN;
    }