9718 update mandoc to 1.14.4

*** 1,6 ****
! /*      $Id: mandoc_aux.c,v 1.10 2017/06/12 19:05:47 schwarze Exp $ */
  /*
   * Copyright (c) 2009, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
--- 1,6 ----
! /*      $Id: mandoc_aux.c,v 1.11 2018/02/07 20:04:57 schwarze Exp $ */
  /*
   * Copyright (c) 2009, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
*** 109,118 ****
  char *
  mandoc_strndup(const char *ptr, size_t sz)
  {
          char    *p;
  
!         p = mandoc_malloc(sz + 1);
!         memcpy(p, ptr, sz);
!         p[(int)sz] = '\0';
          return p;
  }
--- 109,118 ----
  char *
  mandoc_strndup(const char *ptr, size_t sz)
  {
          char    *p;
  
!         p = strndup(ptr, sz);
!         if (p == NULL)
!                 err((int)MANDOCLEVEL_SYSERR, NULL);
          return p;
  }