rem: re_set_syntax (syntax) reg_syntax_t syntax;
add: re_set_syntax (reg_syntax_t syntax)
context: re_set_syntax (syntax)    reg_syntax_t syntax;{  reg_syntax_t ret = re_syntax_options;  re_syntax_options = syntax;# ifdef DEBUG  if (syntax & RE_DEBUG)    debug = 1;  else if (debug) /* was on but now is not */    debug = 0;# endif /* DEBUG */  return ret;}