Rework ipfw rules parsing and printing code.

Introduce show_state structure to keep information about printed opcodes.
Split show_static_rule() function into several smaller functions. Make
parsing and printing opcodes into several passes. Each printed opcode
is marked in show_state structure and will be skipped in next passes.
Now show_static_rule() function is simple, it just prints each part
of rule separately: action, modifiers, proto, src and dst addresses,
options. The main goal of this change is avoiding occurrence of wrong
result of `ifpw show` command, that can not be parsed by ipfw(8).
Also now it is possible to make some simple static optimizations
by reordering of opcodes in the rule.

PR:		222705
Discussed with:	melifaro
MFC after:	2 weeks
Sponsored by:	Yandex LLC

sbin/ipfw/ipfw2.h

@@ -56,6 +56,12 @@ struct cmdline_opts {
 
 };
 
+enum {
+	TIMESTAMP_NONE = 0,
+	TIMESTAMP_STRING,
+	TIMESTAMP_NUMERIC,
+};
+
 extern struct cmdline_opts co;
 
 /*

sbin/ipfw/main.c

@@ -324,11 +324,11 @@ ipfw_main(int oldac, char **oldav)
 			break;
 
 		case 't':
-			co.do_time = 1;
+			co.do_time = TIMESTAMP_STRING;
 			break;
 
 		case 'T':
-			co.do_time = 2;	/* numeric timestamp */
+			co.do_time = TIMESTAMP_NUMERIC;
 			break;
 
 		case 'v': /* verbose */