rules: matchrule stops returning things whose lifetime it does not own

Three findings, one interface.  matchrule handed back a Rule* and a
pointer into a static char[128], both read by the caller after it had
released rulelock:

	e = matchrule(verb, ..., &rule);
	if(rule != nil && rule->log)		/* freed? */
		syslog(0, "fw", "... %s", e);	/* whose? */

A rule set installed between the return and those two lines frees the
Rule under them, which is a narrow window but this is a firewall, and
two procs deciding at once overwrite each other's reason -- in a program
whose entire output is the reason.  netfs.c ran multi-proc from the
first blocking open and had its own static err with the same problem.
Neither is a race you can test for; both stop existing if the answer
lives in the caller's frame, so it does.  Seven positional arguments
become named fields while the signature is being rewritten anyway.

The third is that revalidate could not ask without being counted.  A
rule edit rebuilds the set, so every hit count starts at zero, and then
revalidate re-checks each live flow against the new rules and charged
every one of them to the rule that matched.  So a rule that had decided
nothing since the edit reported one decision per live connection, and
stats answered a different question after every edit.  count says
whether this is traffic.

Also: the log said "deny tcp connect 127.0.0.2" for a connection to a
port it never named.  getfields writes over the separators it splits
on, so f[1] afterwards is only what precedes the first "!".  The
address is copied before it is taken apart.

Four checks.  Two exercise the log path end to end, denied and
permitted, matching the full address and the rule number in
/sys/log/fw -- which they create if it is missing and remove again if
they made it.  One reads the hit count after an edit: with count put
back to 1 in revalidate it reports 1 where 0 is right.  51 pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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