Fix stringop-truncation compile error for gcc9

[EsdeathYZH]

在g++ 9.4.0环境下编译，报了如下错误：

In file included from /usr/include/string.h:495,
                 from /usr/include/python3.8/Python.h:30,
                 from /home/yaozihang/oneflow/oneflow/api/python/framework/tensortype.cpp:16:
In function 'char* strncpy(char*, const char*, size_t)',
    inlined from 'void oneflow::one::generalize_tensor_types()' at /home/yaozihang/oneflow/oneflow/api/python/framework/tensortype.cpp:127:14,
    inlined from 'void OneflowApiPythonModule165(pybind11::module&)' at /home/yaozihang/oneflow/oneflow/api/python/framework/tensortype.cpp:167:26:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:34: error: 'char* __builtin_strncpy(char*, const char*, long unsigned int)' specified bound 64 equals destination size [-Werror=stringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

参考了https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#Warning-Options 中对此warning的描述解决