fix the function _ssub

[ArrogantGao]

In the current code the function _ssub for LongLongUInt is not correct.

function _ssub(x::NTuple{C,UInt}, y::NTuple{C,UInt}, c::Bool) where {C}
    v1, c1 = Base.sub_with_overflow(x[C], y[C])
    if c
        v2, c2 = Base.sub_with_overflow(v1, c)
        c = c1 || c2
        return (_ssub(x[1:C-1], y[1:C-1], c)..., v2)
    else
        return (_ssub(x[1:C-1], y[1:C-1], c1)..., v1)
    end
end

when c == true, it calls Base.sub_with_overflow(v1, c), where v1 is UInt and c is Bool. This function is not supported.

I change the function call to be Base.sub_with_overflow(v1, one(c)) to fix that.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.27%. Comparing base (9e49738) to head (1f0cfed).
Report is 14 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #59      +/-   ##
==========================================
- Coverage   93.07%   91.27%   -1.80%     
==========================================
  Files           7        7              
  Lines         332      470     +138     
==========================================
+ Hits          309      429     +120     
- Misses         23       41      +18     

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[GiggleLiu]

Nice catch, thank you!