Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

pmc: convert native to jsonl and track TSC value of samples

- add '-j' options to filter to enable converting native pmc
log format to json lines format to enable the use of scripts
and external tooling

% pmc filter -j pmc.log pmc.jsonl

- Record the tsc value in sampling interrupts as opposed to
recording nanotime when the sample is copied to a global log
in hardclock - potentially many milliseconds later.

- At initialize record the tsc_freq and the time of day to give
us an offset for translating the tsc values in callchain records