usr.sbin: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

bhyve: Avoid arithmetic on void pointers

No functional change intended.

MFC after: 1 week

bhyve: enable virtio-net mergeable rx buffers for tap(4)

This patch adds a new netbe_peek_recvlen() function to the net
backend API. The new function allows the virtio-net receive code
to know in advance how many virtio descriptors chains will be
needed to receive the next packet. As a result, the implementation
of the virtio-net mergeable rx buffers feature becomes efficient,
so that we can enable it also with the tap(4) backend. For the
tap(4) backend, a bounce buffer is introduced to implement the
peeck_recvlen() callback, which implies an additional packet copy
on the receive datapath. In the future, it should be possible to
remove the bounce buffer (and so the additional copy), by
obtaining the length of the next packet from kevent data.

Reviewed by: grehan, aleksandr.fedorov@itglobal.com
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D23472

Fix several iov handling bugs in bhyve virtio-scsi backend.

- buf_to_iov() does not use buflen parameter, allowing out of bound read.
- buf_to_iov() leaks memory if seek argument > 0.
- iov_to_buf() doesn't need to reallocate buffer for every segment.
- there is no point to use size_t for iov counts, int is more then enough.
- some iov function arguments can be constified.
- pci_vtscsi_request_handle() used truncate_iov() incorrectly, allowing
getting out of buffer and possibly corrupting data.
- pci_vtscsi_controlq_notify() written returned status at wrong offset.
- pci_vtscsi_controlq_notify() leaked one buffer per event.

Reported by: wg
Reviewed by: araujo
MFC after: 1 week
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D18465

- Add bhyve virtio-scsi storage backend support.

Example of configuration:
ctl.conf:
portal-group pg0 {
discovery-auth-group no-authentication
listen 0.0.0.0
listen [::]
}

target iqn.2012-06.com.example:target0 {
auth-group no-authentication
portal-group pg0
port ioctl/5/3

lun 0 {
path /z/test.img
size 8G
}
lun 1 {
path /z/test1.img
size 8G
}
}

bhyve <...> -s 4,virtio-scsi,/dev/cam/ctl5.3,iid=3 <VM_NAME>

From inside guest:
root@:~ # zpool status test
pool: test
state: ONLINE
scan: none requested
config:

NAME STATE READ WRITE CKSUM
test ONLINE 0 0 0
da0 ONLINE 0 0 0
da1 ONLINE 0 0 0

dmesg:
da0 at vtscsi0 bus 0 scbus0 target 0 lun 0
da0: <FREEBSD CTLDISK 0001> Fixed Direct Access SPC-5 SCSI device
da0: Serial Number MYSERIAL0000
da0: 300.000MB/s transfers
da0: Command Queueing enabled
da0: 8192MB (16777216 512 byte sectors)
da1 at vtscsi0 bus 0 scbus0 target 0 lun 1
da1: <FREEBSD CTLDISK 0001> Fixed Direct Access SPC-5 SCSI device
da1: Serial Number MYSERIAL0001
da1: 300.000MB/s transfers
da1: Command Queueing enabled
da1: 8192MB (16777216 512 byte sectors)

Discussed with: grehan
Reviewed by: mav
Obtained from: TrueOS
Relnotes: Yes
Sponsored by: iXsystems Inc.
Tested with: FreeBSD HEAD, Fedora 28 (Workstation) and
Ubuntu 18.04.
Differential Revision: https://reviews.freebsd.org/D15276