Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

I found this when compiling all the bootstrap tools with -fsanitize=addres:

==65590==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x62d000008400 at pc 0x000000473053 bp 0x7ffc1c7dd910 sp 0x7ffc1c7dd0b8
READ of size 32769 at 0x62d000008400 thread T0
    #0 0x473052 in regexec (/local/scratch/alr48/cheri/build/freebsd-amd64-build/local/scratch/alr48/cheri/freebsd/amd64.amd64/tmp/legacy/bin/grep+0x473052)
    #1 0x4c9cf3 in procline /local/scratch/alr48/cheri/freebsd/usr.bin/grep/util.c:539:8
    #2 0x4c8687 in procfile /local/scratch/alr48/cheri/freebsd/usr.bin/grep/util.c:379:18
    #3 0x4c6596 in main /local/scratch/alr48/cheri/freebsd/usr.bin/grep/grep.c:714:8

0x62d000008400 is located 0 bytes to the right of 32768-byte region [0x62d000000400,0x62d000008400)
allocated by thread T0 here:
    #0 0x493d5d in malloc (/local/scratch/alr48/cheri/build/freebsd-amd64-build/local/scratch/alr48/cheri/freebsd/amd64.amd64/tmp/legacy/bin/grep+0x493d5d)
    #1 0x4cad75 in grep_malloc /local/scratch/alr48/cheri/freebsd/usr.bin/grep/util.c:656:13
    #2 0x4c8129 in procfile /local/scratch/alr48/cheri/freebsd/usr.bin/grep/util.c
    #3 0x4c6596 in main /local/scratch/alr48/cheri/freebsd/usr.bin/grep/grep.c:714:8

SUMMARY: AddressSanitizer: heap-buffer-overflow (/local/scratch/alr48/cheri/build/freebsd-amd64-build/local/scratch/alr48/cheri/freebsd/amd64.amd64/tmp/legacy/bin/grep+0x473052) in regexec

Reviewed By:	kevans
MFC after:	1 week

We know up front how many items we can have in the queue (-B/Bflag), so
pay the cost of those particular allocations early on.

The reduced queue maintenance overhead seemed to yield about an ~8%
improvement for my earlier `grep -C8 -r closefrom .` test.

MFC after:	2 weeks

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Metadata printing with -b, -H, or -n flags suffered from a few flaws:

1) -b/offset printing was broken when used in conjunction with -o

2) With -o, bsdgrep did not print metadata for every match/line, just
   the first match of a line

3) There were no tests for this

Address these issues by outputting this data per-match if the -o flag is
specified, and prior to outputting any matches if -o but not --color,
since --color alone will not generate a new line of output for every
iteration over the matches.

To correct -b output, fudge the line offset as we're printing matches.

While here, make sure we're using grep_printline in -A context.  Context
printing should *never* look at the parsing context, just the line.

The tests included do not pass with gnugrep in base due to it exhibiting
similar quirky behavior that bsdgrep previously exhibited.

Submitted by:	Kyle Evans <kevans91@ksu.edu>
Reviewed by:	cem
Differential Revision:	https://reviews.freebsd.org/D10580

Previously, when given a negative -A/-B/-C argument bsdgrep would
overflow the respective context flag(s) and exhibited surprising
behavior.

Fix this by removing unsignedness of Aflag/Bflag and erroring out if
we're given a value < 0.  Also adjust the type used to track 'tail'
context in procfile() so that it accurately reflects the Aflag value
rather than overflowing and losing trailing context.

This also fixes an inconsistency previously existing between -n and
-C "n" behavior.  They are now both limited to LLONG_MAX, to be
consistent.

Add some test cases to make sure grep errors out properly for both
negative context values as well as non-numeric context values rather
than giving bogus matches.

Submitted by:	Kyle Evans <kevans91@ksu.edu>
Reviewed by:	cem
Differential Revision:	https://reviews.freebsd.org/D10675

-w flag matching with an empty pattern was generally 'broken', allowing
matches to occur on any line whether or not it actually matches -w
criteria.

This fix required a good amount of refactoring to address.  procline()
is altered to *only* process the line and return whether it was a match
or not, necessary to be able to short-circuit the whole function in case
of this matchall flag. -m flag handling is moved out as well because it
suffers from the same fate as context handling if we bypass any actual
pattern matching.

The matching context (matches, mostly) didn't previously exist outside
of procline(), so we go ahead and create context object for file
processing bits to pass around.  grep_printline() was created due to
this, for the scenarios where the matches don't actually matter and we
just want to print a line or two, a la flushing the context queue and
no -o or --color specified.

Damage from this broken behavior would have been mitigated by the fact
that it is unlikely users would invoke grep -w with an empty pattern.

This was identified while checking PR 105221 for problems it this may
cause in BSD grep, but PR 105221 is *not* a report of this behavior.

Submitted by:	Kyle Evans <kevans91 at ksu.edu>
Differential Revision:	https://reviews.freebsd.org/D10433