Remove the unused "confidence" member of the Port class. This is not the same

as the "name_confidence" member of a service match. I grepped the whole source
tree and couldn't find any reference to "confidence" besides its declaration
and initialization; it builds fine without it.

portlist.cc

@@ -120,7 +120,7 @@ Port::Port() {
   owner = NULL;
   rpc_status = RPC_STATUS_UNTESTED;
   rpc_program = rpc_lowver = rpc_highver = 0;
-  state = confidence = 0;
+  state = 0;
   next = NULL;
   serviceprobe_results = PROBESTATE_INITIAL;
   serviceprobe_service = NULL;

portlist.h

@@ -224,7 +224,6 @@ class Port {
   u8 proto;
   char *owner;
   int state; 
-  int confidence; /* How sure are we about the state? */
   state_reason_t reason;
 
 #ifndef NOLUA