9718 update mandoc to 1.14.4

@@ -1,6 +1,6 @@
-/*      $Id: mdoc.c,v 1.267 2017/06/17 13:06:16 schwarze Exp $ */
+/*      $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

@@ -295,12 +295,12 @@
                 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 ||
+                    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 == ' ')