sys: Remove $FreeBSD$: two-line .h pattern

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

Framework for ARM64 instruction disassembler

Provide an easy to use framework for ARM64 DDB disassembler.
This commit does not contain full list of instruction opcodes.

Obtained from: Semihalf
Sponsored by: Cavium
Approved by: cognet (mentor)
Reviewed by: zbb, andrew, cognet
Differential revision: https://reviews.freebsd.org/D5114