Remove $FreeBSD$: two-line .h pattern

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

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

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

top(1): fixed the empty output problem in non-interactive mode (-n, -b) regressed in r336028

PR: 229842
Reported by: Ali Abdallah <aliovx@gmail.com>
Reviewed by: eadler, cy
Approved by: gnn (mentor)
Differential Revision: https://reviews.freebsd.org/D16455

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): remove special handling of load > 5

When the load is "high" (an arbitrary value) top(1) previously moved the
cursor to the top-left of the screen as an acknowledgment. In practice,
on modern machines, even relatively slow ones, it looked more like a
glitch. Remove the logic.

top(1): move command mapping to commands.c

This eliminates the difficult to follow mapping of a string list. It
moves numbers from "#define" into (more) debuggable enums. More
generally, it follows the trend of moving more data into a more central
mechanism.

The help output is a little worse: " " is not rendered well, and there
are duplicate entries, but that will be fixed in a followup.

top(1): Fix two speeling errors I introduced

top(1): cleanup memory allocation and warnings

- Prefer calloc over malloc. This is more predicable and we're not in a
performance sensitive context. [1]
- Remove bogus comment (obsolete from prior commit). [2]
- Remove void casts and type casts of NULL
- Remove redundant declaration of 'quit'
- Add additional const

Reported by: kib [1], vangyzen [2]

top(1): remove wrapper around putchar

This appears to have been written for portability which we no longer
need.

top(1): clean up a bit

- remove unused defines
- use standard defines for STDOUT
- don't cast for memset
- avoid using (void) cast

top(1): Use uid_t for uid rather than 'int'

Remove unneeded define while here.

top(1): Use standard boolean rather than homegrown alternative

top(1): ansify, style(9). and nits

- Prefer using ansi prototypes rather than C prototypes
- Keep type on separate line from name of function
- Try to keep things const where possible. This will help get to WARNS=6
- switch to "bool" where it makes sense

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): clean much of WARNS=3 issues

There is still one glaring issue: new_message is not a protoype, but
can't be trivially converted since it uses K&R style var-args.

top(1): build with WARN=2

top(1): unconditionally assume we are on FreeBSD (more unifdef)

Now that we're our own upstream, remove useless ifdefs.

Retry revert

I had a local modification before my revert. Try reverting one more time.

revert r333928

I had missed a file when testing this, and it does not build. Will try again.

top(1): unconditionally assume we are running on FreeBSD

This allows us to remove a special header and more specifically just the
system headers we want.

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