Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

top(1): support command name and argument grepping

Obtained from: OpenBSD
Reviewed by: imp@
Pull Request: https://github.com/freebsd/freebsd-src/pull/479

top(1): Use warnx and errx instead of fprintf

This also makes make "-v" exit without error, since it isn't.

top(1): rollback r335836

Encoding-specific processing introduced in r335836 is not recommended.
And doing getenv("LANG") and assuming an encoding based on it is a
very bad practice to internationalize software.

Submitted by: hrs
Differential Revision: https://reviews.freebsd.org/D16203

Changed to eliminate the upper limit of command length displayed
by "-a" and expand to match terminal width

Reviewed by: eadler
Approved by: gnn (mentor)
Differential Revision: https://reviews.freebsd.org/D16083

top(1) - support UTF-8 display

Reviewed by: eadler
Approved by: gnn (mentor)
Differential Revision: https://reviews.freebsd.org/D16006

top(1): remove trailing whitespace

top(1): style and related

- style(9)
- remove now-defunct comments
- remove getuid check for low delay
- expand range of format_k

top(1): bring some structure to commands

Right now this is only used for help text but it'll eventually be used
to build up long options array, dispatch commands, etc.

top(1): filter fewer warnings; clean up

- remove WARNS?=6. It is default
- we no longer have cast-qual problems
- remove unused macros
- remove unneeded casts
- add include guard for loadavg.h

top(1): permit sub-second delay times

This removes the getuid check for delay==0. It didn't prevent users from
writing similar programs in the general case. In theory, if top(1) is
among one of the few restricted programs you're allowed to run, it may
have helped a little, but there are better ways of handling that case.

top(1): use a different command to toggle tid vs pid

- By popular demand, implement a different switch ("T") for toggling
between thread id and process id.
- Add an assert that the size of command chars is as expected.
- Also clean up some messiness I found when implementing this.
- Further document the new flag.

Requested by: flo, ronald-lists@klop.ws, bapt
PR: 139389 (for the record)
X-MFC-With: r334474

top(1): another pass of cleanup

- avoid the need to call a function to get size of known array. I'll
likely re-arrange some of the indirect in a later to avoid the magic
constants.
- use correct type
- add const
- replace caddr_t with void*. This corrects an alignment warning.
- remove duplicated include from immediately prior commit

Under base clang we're now down to:
- 3 warning in top.c, 1 warning in mahcine.c, 4 warning in display.c,
- 1 warning in utils.c

Tested with base clang, gcc7, gcc9, base gcc (mips)

top: add -p option and p command to only show a single process

Allow to show only a single process specified by PID. This could
be done either by running top like 'top -p PID' or using the 'p' command
inside top.

Reviewed by: eadler
Approved by: eadler
Obtained from: OpenBSD
Differential Revision: https://reviews.freebsd.org/D15501

top(1): modernize a bit; reduce warnings

- Replace caddr_t with "void *". This reduces
the number of warnings at WARNS=6
- use "static" where possible
- sprinkle const where possible

This leaves at WARNS=6:
35 warnings in top.c
88 warnings in machine.c
7 warnings in commands.c

all of which are either "incompatible-pointer-types-discards-qualifiers"
or "cast-qual"

Revert r333969 which contained one too many changes

top(1): modernize a bit; reduce warnings

- Replace caddr_t with "void *". This reduces
the number of warnings at WARNS=6
- use "static" where possible
- sprinkle const where possible

This leaves at WARNS=6:
35 warnings in top.c
72 warnings in machine.c
5 warnings in commands.c

all of which are either "incompatible-pointer-types-discards-qualifiers"
or "cast-qual"

top(1): fix several more warnings

top(1): pull function declarations and externs into headers

top(1): pull configuration directly into header files

This sets configuration variables directly in the various header files,
avoiding the need to have special logic in our Makefile to build the
header.

top(1): Quiesce several warnings

This is all warnings at level six (6) that are not
char-subscripts, incompatible-pointer-types,
sign-compare, switch, int-conversion,
missing-variable-declarations, cast-qual, cast-align

Some warnings that are fixed by this commit are:
shadow, strict-prototypes, missing-prototypes, pointer-arith,
unused-parameter, unused-const-variable, and several others

top(1): unconditionally provide 'FreeBSD' as a version

top(1): Migrate top to usr.bin

We've been maintaining top(1) for a long time, and the upstream
hasn't existed/been used in similarly as long. Make it clear that we own
top(1)

Tested with 'make universe'. Everything passed except MIPS which failed
for unrelated reasons. Install also tested for amd64.

Reviewed by: sbruno
No objections: imp, mmacy
Differential Revision: https://reviews.freebsd.org/D15387