Support kernel tracing in drcachesim for system calls

This issue is to track the design and implementation for the support to trace kernel instructions and data addresses for system calls in drcachesim.

The current plan is to use Intel-PT to collect system call instruction traces in the drcachesim tracer. We can start kernel tracing by using perf_events_open + ioctl in a pre-syscall event, and end it using ioctl in a post-syscall event.

We can then convert the PT trace to a drcachesim trace using libipt, and interleave it into the user-mode trace gathered by drcachesim, in raw2trace.

An approximation of the data addresses accessed by the kernel can be reconstructed using some heuristics and metadata collected by drcachesim (e.g. system call parameters). There are some interesting research articles that implement similar techniques: https://ieeexplore.ieee.org/document/9065578.