libsa: Remove redundant sys/cdefs.h

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

stand: Make sure nobody has a NULL pointer for dv_cleanup

dv_cleanup is specified almost everywhere. Use nullsys instead of NULL
to indicate 'do nothing'. Also, be consistent in trailing commas that
were missing before.

Sponsored by: Netflix
Reviewed by: tsoome
Differential Revision: https://reviews.freebsd.org/D35913

stand: Use c99 structure initialization for userboot's host_fsops

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stand/userboot: Kill set but unused variables

We never use 'dev' after fetching it from the varargs list. Skip the
whole bother of fetching it, or setting up the meachinery to fetch it.

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Fix pkgfs stat so it satisfies libsecureboot

We need a valid st_dev, st_ino and st_mtime
to correctly track which files have been verified
and to update our notion of time.

ve_utc_set(): ignore utc if it would jump our current time
by more than VE_UTC_MAX_JUMP (20 years).

Allow testing of install command via userboot.
Need to fix its stat implementation too.

bhyveload also needs stat fixed - due to change to userboot.h

Call ve_error_get() from vectx_close() when hash is wrong.

Track the names of files we have hashed into pcr

For the purposes of measured boot, it is important
to be able to reproduce the hash reflected in
loader.ve.pcr
so loader.ve.hashed provides a list of names in the order they
were added.

Reviewed by: imp
MFC after: 1 week
Sponsored by: Juniper Networks
Differential Revision: https://reviews.freebsd.org//D24027

libsa: Const-ify buffer argument of write(2) analog

Reported by: kevans
Reviewed by: delphij, eadler, imp, kevans
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D14482

Move sys/boot to stand. Fix all references to new location

Sponsored by: Netflix