TVM multithread for windows

meet a problem that the program can not to break for ever when I use multithread with the vs2017 of windows.when i trace the code of runtime , finding the problem is located at (tvm/src/runtime/thread_pool.cc at 60769b77f9abe29aafabda4d5d1cd625e7c61f9f · apache/tvm · GitHub)

this problem how to server ??

another problem is that when I not open the thread with vs2017, the destructor of workpool class can not be executed ,it can cause a leak memory.

@yidawang, @FrozenGene

@hcho3 If you have some spare circles, can you take a look at this issue on Windows? Let me know if you can reproduce the problem. Thanks.