rem: init_syntax_once ()
add: init_syntax_once (void)
context: init_syntax_once (){   register int c;   static int done = 0;   if (done)     return;   bzero (re_syntax_table, sizeof re_syntax_table);   for (c = 0; c < CHAR_SET_SIZE; ++c)     if (ISALNUM (c))	re_syntax_table[c] = Sword;   re_syntax_table['_'] = Sword;   done = 1;}