[bug] 数字+量词+名词组合处理不当

```Cpp
    std::string s = "购买了3部手机";
    std::vector<std::string> expected = {"购买", "了", "3", "部", "手机"};
    jieba.Cut(s, words, true);
    EXPECT_EQ(words, expected);
```

预期结果应该是: 购买 了 3 部 手机
你的代码切分结果: 购买 了 3 部手机