Perf data files cannot be processed until the header is updated which is
done via an on_exit handler.
If perf is killed due to a SIGTERM it does not run the on_exit hooks
leaving the perf.data file in a random state which perf-report will
happily spin on trying to read.
As noted by Mike an easy reproducer is:
perf record -a -g & sleep 1; killall perf
Fix by catching SIGTERM like it does SIGINT.
Also need to remove the kill which was added via commit f7b7c26e.