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): reimplement header formatting as sbuf

The current header formatting is a giant format string that changes
global state during the format process.

Make the following changes:
- use sbuf to build up the header rather than use the above
pseudo-dynamic one
- Change name length to 10
- Reduce size of RES and SIZE by making humanize more aggressive
- Restore a version number line to the copyright. This may be required
by the copyright (and may not be; its unclear)

This is also a pre-req to implementing TOPCOLOR from newer versions of
top(1)

Discussed with: allanjude, rpolka, danfe, rgrimes
Differential Revision: https://reviews.freebsd.org/D15801

top(1): Fix Coverity warning

Don't call strerror on negative errnos

Reported by: Coverity
CID: 976708
Reviewed by: eadler
Differential Revision: https://reviews.freebsd.org/D15909

top(1): format help more nicely

For entries that are duplicates present them nicely rather than showing
two identical help entries. For ' ' present it as SPC

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): 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): use modern interfaces for nice and related

- attempt and fail, rather than check for permission.
- use macro rather than explicit "-20"

top(1): add command aliases; correct dumb support

top(1): use sys_signame instead of hard coding signals

This enables the removal of the signal.h awk script. Shamelessly stolen
from kill(1).

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): permit sending signal with any 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): some nitpicks

- prefer fully spelled names to "u_long"
- fix speeling

top(1): include what you use

- Change headers to more closely match what we use
- use more standard functions instead of bzero, bcmp, bcopy
- Add myself to authors.

Tested with: base clang (amd64), gcc 9 (amd64), base clang (i386), base
gcc (mips)

top(1): misc minor improvements

- use bool instead of int [0]
- use calloc correctly [0]
(this also caught an incorrect sizeof argument) [1]
- use size_t over int [2]
- correct style

Reported by: pfg [0], scan-build [1], gcc [2]

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): Use standard boolean rather than homegrown alternative

top(1): remove two unneeded headers

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): unbreak build with gcc7; fix varargs

- use correct function for varargs argument
- allow build to complete with gcc7 at current WARNS

Reported by: jhibbits, ian

top(1): clean up some "const" related warnings

This leaves at WARNS=6:
35 warnings in top.c
88 warnings in machine.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): clean up in prep for const poisoning

- sprinkle "const" in a few obvious places
- remove "(void)" in front of lack-of-error-checked functions

top(1): further unconditionally assume we're on FreeBSD

top(1): fix several more warnings

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

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): remove use of 'register' keyword

This keyword is meaningless is obscures future diffs that help clear up
warnings in top.

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): unconditionally provide 'FreeBSD' as a version

top(1): assume that we're building on FreeBSD

This allows us to avoid the ifdefs that we set unconditionally.

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