Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

This library allows for user space applications to check file descriptors
or paths to see if they can be verified by MAC/veriexec.

Reviewed by: jtl, wblock
Obtained from: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D8562