When performing an inverted search in less, make sure to invalidate the match
bounds prior calling regexec(). In this inverted scenario a match is found when
regexec() returns false causing the bounds to not be updated. This is
problematic since the bounds will then refer to a previous match and future
pointer arithmetic will eventually be off which is manifested in a SIGSEGV.

Issue reported by Larry Hynes on tech@
ok martijn@ tb@

remove fancy null check function in favor of checking for null.
from Ricardo Mestre

error() is not a stdarg function, so there is no reason for NULL_PARG
to be special. Simply use NULL.

Garrett D'Amore has agreed to moving his copyright line up above the
terms with the existing copyright, so it is clear it applies the same
terms.

Replace less with the cleaned-up fork of less 458 maintained by Garrett
D'Amore at https://github.com/gdamore/less-fork. This has significantly
less portability goop, has a tidied up code style, uses terminfo instead
of termcap, and is has stricter POSIX compliance.

Many of our local changes have been accepted upstream: substantial
remaining local changes are code to read help files from /usr/share
rather than compiling them in, man page and help improvements, and some
tweaks to the default options.

Review and testing by millert, ok deraadt

When invoked as more, make the -i option behave the same as less's
-I to match POSIX. OK and man bits from jmc@

Use REG_STARTEND to permit searches to work past/across NUL bytes.

ok millert@ shadchin@

Merge Less 458 plus local patches

ok guenther@, ok jmc@ for man bits

Unlike less, more should use basic regular expressions.
OK schwarze@

branches: 1.1.1;
Initial revision