magic-trace does not stop running on process SIGKILL

[kaajalbgupta]

When running magic-trace to trace a process, when SIGKILL is sent to the traced process, the magic-tracer does not stop running, while perf record does stop. I expected the magic tracer to stop running or to take a snapshot immediately upon the process finishing. To reproduce the issue:

1. Run sleep 5000 and get its PID.
2. Run magic-trace attach -p <pid> -o magic-trace.fxt
3. Run kill -9 <pid> to see that perf record stops running while magic-trace does not.

Running version 6.7.0 of perf userspace tools.