try to allow just 'option'

In many cases, DER defines something like

	ATTRIBUTE foo 1 type option=1

this seems redundant.

We make provisions for allowing just 'option', which could then
take the option number from the attribute number.

However, the function dict_read_process_attribute() initializes
the attribute number _after_ processing the flags / type field.

Once that code has been tweaked to parse the attribute number
first, this new DER code will work.  At that point, the DER
dictionaries can be updated with the following Perl script:

perl -p -i -e 'next if !/^ATTR/;s/option=\d+/option/' share/dictionary/der/dictionary*

src/protocols/der/base.c

@@ -361,12 +361,28 @@ static int dict_flag_max(fr_dict_attr_t **da_p, char const *value, UNUSED fr_dic
 	return 0;
 }
 
-static int dict_flag_option(fr_dict_attr_t **da_p, UNUSED char const *value, UNUSED fr_dict_flag_parser_rule_t const *rules)
+static int dict_flag_option(fr_dict_attr_t **da_p, char const *value, UNUSED fr_dict_flag_parser_rule_t const *rules)
 {
 	fr_der_attr_flags_t *flags = fr_dict_attr_ext(*da_p, FR_DICT_ATTR_EXT_PROTOCOL_SPECIFIC);
 	unsigned long num;
 	char *end = NULL;
 
+	/*
+	 *	In the interest of laziness, allow a bare 'option', so
+	 *	that we don't have to give an attribute number, and
+	 *	then also duplicate that numbr in 'option='.
+	 */
+	if (!value) {
+		if (!(*da_p)->state.attr_set || (*da_p)->attr > 0x1f) {
+			fr_strerror_printf("Missing value for 'option='");
+			return -1;
+		}
+
+		flags->class = FR_DER_CLASS_CONTEXT;
+		flags->option = (*da_p)->attr;
+		return 0;
+	}
+
 	/*
 	 *	We limit the allowed options (tag numbers) to ones
 	 *	which fit into the 5 bits of the first byte.  We don't
@@ -378,9 +394,8 @@ static int dict_flag_option(fr_dict_attr_t **da_p, UNUSED char const *value, UNU
 		return -1;
 	}
 
-	/*
-	 *	Don't over-ride 'class==foo,option=bar'
-	 */
+	fr_assert(!(*da_p)->state.attr_set);
+
 	flags->class = FR_DER_CLASS_CONTEXT;
 	flags->option = num;
 
@@ -397,7 +412,7 @@ static const fr_dict_flag_parser_t  der_flags[] = {
 	{ L("is_pair"),		{ .func = dict_flag_is_pair } },
 	{ L("is_pairs"),	{ .func = dict_flag_is_pairs } },
 	{ L("max"),		{ .func = dict_flag_max, .needs_value = true } },
-	{ L("option"),		{ .func = dict_flag_option, .needs_value = true } },
+	{ L("option"),		{ .func = dict_flag_option} },
 	{ L("sequence_of"),	{ .func = dict_flag_sequence_of, .needs_value = true } },
 	{ L("set_of"),		{ .func = dict_flag_set_of, .needs_value = true } },
 };