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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

- Trim an unused and bogus Makefile for mount_smbfs.
- Reconnect with some minor modifications, in particular now selsocket()
internals are adapted to use sbintime units after recent'ish calloutng
switch.

Disconnect non-MPSAFE SMBFS from the build in preparation for dropping
GIANT from VFS. In addition, disconnect also netsmb, which is a base
requirement for SMBFS.

In the while SMBFS regular users can use FUSE interface and smbnetfs
port to work with their SMBFS partitions.

Also, there are ongoing efforts by vendor to support in-kernel smbfs,
so there are good chances that it will get relinked once properly locked.

This is not targeted for MFC.

Disconnect non-MPSAFE NTFS from the build in preparation for dropping
GIANT from VFS. This code is particulary broken and fragile and other
in-kernel implementations around, found in other operating systems,
don't really seem clean and solid enough to be imported at all.
If someone wants to reconsider in-kernel NTFS implementation for
inclusion again, a fair effort for completely fixing and cleaning it
up is expected.

In the while NTFS regular users can use FUSE interface and ntfs-3g
port to work with their NTFS partitions.

This is not targeted for MFC.

Disconnect non-MPSAFE NWFS from the build in preparation for dropping
GIANT from VFS. In addition, disconnect also netncp, which is a base
requirement for NWFS.

In the possibility of a future maintenance of the code and later
readd to the FreeBSD base, maybe we should think about a better location
for netncp. I'm not entirely sure the / top location is actually right,
however I will let network people to comment on that more specifically.

This is not targeted for MFC.

- Commit work from libprocstat project. These patches add support for runtime
file and processes information retrieval from the running kernel via sysctl
in the form of new library, libprocstat. The library also supports KVM backend
for analyzing memory crash dumps. Both procstat(1) and fstat(1) utilities have
been modified to take advantage of the library (as the bonus point the fstat(1)
utility no longer need superuser privileges to operate), and the procstat(1)
utility is now able to display information from memory dumps as well.

The newly introduced fuser(1) utility also uses this library and able to operate
via sysctl and kvm backends.

The library is by no means complete (e.g. KVM backend is missing vnode name
resolution routines, and there're no manpages for the library itself) so I
plan to improve it further. I'm commiting it so it will get wider exposure
and review.

We won't be able to MFC this work as it relies on changes in HEAD, which
was introduced some time ago, that break kernel ABI. OTOH we may be able
to merge the library with KVM backend if we really need it there.

Discussed with: rwatson