timecounting: deprecate time_second(9), time_uptime(9)

time_second(9) has been replaced in the kernel by gettime(9).
time_uptime(9) has been replaced in the kernel by getuptime(9).

New code should use the replacement interfaces. They do not suffer
from the split-read problem inherent to the time_* variables on 32-bit
platforms.

The variables remain in sys/kern/kern_tc.c for use via kvm(3) when
examining kernel core dumps.

This commit completes the deprecation process:

- Remove the extern'd definitions for time_second and time_uptime
from sys/time.h.
- Replace manpage cross-references to time_second(9)/time_uptime(9)
with references to microtime(9) or a related interface.
- Move the time_second.9 manpage to the attic.

With input from dlg@, kettenis@, visa@, and tedu@.

ok kettenis@

missing colon; from Rob Pierce <rob at 2keys dot ca>

Long overdue updates for timecounter changes.
Feedback from jmc@, ok guenther@ for an earlier version.

Remove useless quoting from .Fo and .Fn function names, to prevent
development of a cargo cult in case people look at existing files
for examples. This achieves a consistent .Fo and .Fn quoting style
across the whole tree.

Replace old-fashioned .Fd by new-fangled .In for #include lines.
Diff from Jan Klemkow <j dot klemkow at wemelug dot de> on tech@.
No objection from jmc@ against this type of change.

convert to new .Dd format;

put "CODE REFERENCES" before "SEE ALSO" for consistency

ok jmc@

typos from Jonathon Gray;

typos;

md5(9): ok tedu@

.Xr's for section9:

- MLINKS for uvm stuff
- MLINK vgone.9 vgonel.9
- typos
- fixed SYNOPSIS of extattr(9)

lots of help from miod and art
ok miod@ art@

date should be written formally: .Dd Month day, year
also fixes a few misspellings of the month
ok henning@ jmc@

the the

Add a man page for the much referenced hardclock(9).

Thanks to niklas@, fgs@, mpech@ for feedback.

missing colon; from Rob Pierce <rob at 2keys dot ca>

Long overdue updates for timecounter changes.
Feedback from jmc@, ok guenther@ for an earlier version.

Remove useless quoting from .Fo and .Fn function names, to prevent
development of a cargo cult in case people look at existing files
for examples. This achieves a consistent .Fo and .Fn quoting style
across the whole tree.

Replace old-fashioned .Fd by new-fangled .In for #include lines.
Diff from Jan Klemkow <j dot klemkow at wemelug dot de> on tech@.
No objection from jmc@ against this type of change.

convert to new .Dd format;

put "CODE REFERENCES" before "SEE ALSO" for consistency

ok jmc@

typos from Jonathon Gray;

typos;

md5(9): ok tedu@

.Xr's for section9:

- MLINKS for uvm stuff
- MLINK vgone.9 vgonel.9
- typos
- fixed SYNOPSIS of extattr(9)

lots of help from miod and art
ok miod@ art@

date should be written formally: .Dd Month day, year
also fixes a few misspellings of the month
ok henning@ jmc@

the the

Add a man page for the much referenced hardclock(9).

Thanks to niklas@, fgs@, mpech@ for feedback.