sys: Remove $FreeBSD$: one-line .c comment pattern

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

add floatingpoint.h for arm64

On other architectures floatingpoint.h is a symlink to
machine/floatingpoint.h which in turn includes machine/ieeefp.h.
Do this on arm64 as well for now.

Sponsored by: The FreeBSD Foundation