less: allow use of last column of terminal

less: allow use of last column of terminal

When read_lines tests whether a character will fit on the current
line it checks the *next* character but in case of overflow doesn't
display the *current* one.  This results in the last column of the
terminal never being used.

The test in re_wrap (used when the terminal width changes or line
numbers are enabled/disabled) is different:  it does allow the use
of the final column.

function                                             old     new   delta
read_lines                                           764     770      +6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 6/0)                 Total: 6 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>