Remove $FreeBSD$: one-line sh pattern

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

bhyve: Move libcasper dependecy to lib9p

libcasper(3) is not used in bhyve. So move dependency to the appropriate
place.

Reviewed by: markj
MFC after: 1 week
Sponsored by: vStack
Differential Revision: https://reviews.freebsd.org/D38905

lib9p: fix building on systems without capser

PR: 252353

Add virtio-9p (aka VirtFS) filesystem sharing to bhyve.

VirtFS allows sharing an arbitrary directory tree between bhyve virtual
machine and the host. Current implementation has a fairly complete support
for 9P2000.L protocol, except for the extended attribute support. It has
been verified to work with the qemu-kvm hypervisor.

Reviewed by: rgrimes, emaste, jhb, trasz
Approved by: trasz (mentor)
MFC after: 1 month
Relnotes: yes
Sponsored by: Conclusive Engineering (development), vStack.com (funding)
Differential Revision: https://reviews.freebsd.org/D10335