Replaces OS dependent API with standard cpp libraries in the
```tvm_rpc``` tool.
---
* Replace all filesystem calls with safe and portable std::filesystem
* Worker process remains fork()-ed (POSIX), due to kill() enforcement on
timeout
* Timer process is migrated from fork() to main with WNOHANG (nonblock)
pid watcher
* Watch a single fork()-ed worker, no more "guess" on which fork() will
"die/end" first
* Cleanup ambiguous doc entries, consistent default parameters across
various places
Currently tested with real tuning processes but limited to linux
machines.
Balint Cristian
1b900a3868