Adds a DynamoRIO extension to provide APIs for online PT tracing.
- Adds drpttracer. It is a DynamoRIO extension that provides start PT tracing and end PT tracing APIs.
- Adds the documentation of drpttracer, which contains usage about how to use drpttracer to trace PT.
- Adds drpttracer-test.dll.c. It is a test client that uses drpttracer to record PT traces for every syscall. It starts the Kernel PT tracing in pre syscall callbacks and ends the Kernel PT tracing in post syscall callbacks.
Issue: #5505