PTRACE HARDENING: slight updates.
Merge branch 'hardened/current/log' into hardened/current/ptrace
PTRACE HARDENING: first steps of the integrations of opntr changes about logs.
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Move rl(4) to dev/rl.
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
Mechanically convert to if_inc_counter().
vt(4): Remove vt_buf->vb_dirtymask

This structure and the associated functions were unused since the
implementation of vd_bitblt_text_t callbacks.

MFC after:	3 days
Fix inverted expression to report block size in mode page block descriptor.
- Provide igb_get_counter() to return counters that are not collected,
  but taken from hardware.
- Mechanically convert to if_inc_counter() the rest of counters.
vt(4): Rewrite history scrolling

It's now possible to scroll up the 500 hard-coded lines of history, not
just a fraction of them. For instance, one can reach the top of the boot
process.

Sometimes, when scrolling or when changing the screen size (by changing
the font or loading a KMS driver for instance), one could see the
history cycling (old content appeared below latest lines). This is
fixed.

Now, when the resolution changes are more lines can be shown, the
displayed area is adjusted so that, if the screen was filled with
content before, it's filled with content after as well: more history
is visible, instead of having blank lines below the previously visible
content.

MFC after:	3 days
vt(4): Remove superfluous word in comment

Submitted by:	brueffer@
MFC after:	3 days
MFC with:	271871
Fix static kernel build with options ZFS

This was broken by r271802.

MFC after:	1 week
X-MFC-With:	r271802
Sponsored by:	Multiplay
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'freebsd/master' into hardened/current/hardening
Merge remote-tracking branch 'freebsd/master' into hardened/current/segvguard
Merge remote-tracking branch 'freebsd/master' into hardened/current/ptrace
Merge remote-tracking branch 'freebsd/master' into hardened/current/log