Patch to avoid out of bounds assert with a debug build on Windows.

[dlemstra]

This patch fixes an out of range assert with a debug build on Windows:

    _NODISCARD _CONSTEXPR20 const _Ty& operator[](const size_type _Pos) const noexcept /* strengthened */ {
        auto& _My_data = _Mypair._Myval2;
#if _CONTAINER_DEBUG_LEVEL > 0
        _STL_VERIFY(
            _Pos < static_cast<size_type>(_My_data._Mylast - _My_data._Myfirst), "vector subscript out of range");
#endif // _CONTAINER_DEBUG_LEVEL > 0

        return _My_data._Myfirst[_Pos];
    }

This happens when idx + size == indata.size() and can be avoided by getting the address of the last element and then adding 1 to the pointer.