[C++] sample property

Reference: https://msdn.microsoft.com/zh-tw/library/2f1ec0b1.aspx

using namespace System;

ref class C
{
public:
    property int Size;
};

int main()
{
    C^ c = gcnew C;
    c->Size = 111;
    Console::WriteLine("c->Size = {0}", c->Size);
}