Makes sure g_last_error is null terminated. (#7190)
Makes sure g_last_error is null terminated. (#7190)

This addresses GCC 10 error:

```
"src/runtime/crt/common/crt_runtime_api.c"
include/tvm/runtime/c_runtime_api.h: 在函数‘TVMAPISetLastError’中:
src/runtime/crt/common/crt_runtime_api.c:42:3: 错误：‘strncpy’ specified
bound 1024 equals destination size [-Werror=stringop-truncation]
   42 |   strncpy(g_last_error, msg, sizeof(g_last_error));
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1：所有的警告都被当作是错误
```
Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1