8993 sync regcomp(3C) with upstream

*** 184,189 ****
--- 184,190 ----
          sopno nplus;            /* how deep does it nest +s? */
  };
  
  /* misc utilities */
  #define OUT     (CHAR_MIN - 1)  /* a non-character value */
+ #define IGN     (CHAR_MIN - 2)
  #define ISWORD(c)       (iswalnum((uch)(c)) || (c) == '_')