parser: fix prefix dump to include priority

The original patch adding priority to the set of prefixes failed to
update the prefix dump to include the priority priority field.

Fixes: e3fca60d1 ("parser: add the ability to specify a priority prefix to rules")

Signed-off-by: John Johansen <john.johansen@canonical.com>

parser/rule.h

@@ -182,6 +182,8 @@ public:
 	{
 		bool output = true;
 
+		if (priority != 0)
+			os << "priority=" << priority << " ";
 		switch (audit) {
 		case AUDIT_FORCE:
 			os << "audit";