9718 update mandoc to 1.14.4

*** 1,6 ****
! /*      $Id: mdoc.c,v 1.267 2017/06/17 13:06:16 schwarze Exp $ */
  /*
   * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2010, 2012-2017 Ingo Schwarze <schwarze@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
--- 1,6 ----
! /*      $Id: mdoc.c,v 1.268 2017/08/11 16:56:21 schwarze Exp $ */
  /*
   * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2010, 2012-2017 Ingo Schwarze <schwarze@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
*** 295,306 ****
                  if (c - buf < offs + 2)
                          continue;
                  if (end - c < 3)
                          break;
                  if (c[1] != ' ' ||
!                     isalpha((unsigned char)c[-2]) == 0 ||
!                     isalpha((unsigned char)c[-1]) == 0 ||
                      (c[-2] == 'n' && c[-1] == 'c') ||
                      (c[-2] == 'v' && c[-1] == 's'))
                          continue;
                  c += 2;
                  if (*c == ' ')
--- 295,306 ----
                  if (c - buf < offs + 2)
                          continue;
                  if (end - c < 3)
                          break;
                  if (c[1] != ' ' ||
!                     isalnum((unsigned char)c[-2]) == 0 ||
!                     isalnum((unsigned char)c[-1]) == 0 ||
                      (c[-2] == 'n' && c[-1] == 'c') ||
                      (c[-2] == 'v' && c[-1] == 's'))
                          continue;
                  c += 2;
                  if (*c == ' ')