Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: less v451.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

MFV: Update to less v443.

MFC after: 1 month

Update less to v436. This is considered as a bugfix release from vendor.

Major changes from v429:
* Don't pass "-" to non-pipe LESSOPEN unless it starts with "-".
* Allow a fraction as the argument to the -# (--shift) option.
* Fix highlight bug when underlined/overstruck text matches at end of line.
* Fix non-regex searches with ctrl-R.

Approved by: re (kensmith, kib)

Vendor import of less v436.